I went to GM air conditioning school in the early 70's. Those compressors were 6 cylinders where others were 2 cylinders. They did not use a cycling clutch as most others. They had 3 sets of 2 pistons controlled by a swash plate and kept the pressures correct. Some also were controlled by a thermostat dial which turned on heat or ac or blend to keep the temp correct. No electronics, all mechanical. Great system.
That's great info! I wasn't aware the A6 compressors kept the pressure correct. I'm learning as I go about these systems. My GM car is R134a converted with a POA valve eliminator. I wish I kept the old POA valve and used the screw/bolt to adjust evaporator pressure for r134a. I'm not having any problems with the POA eliminantor but the compressor never goes off. Is this because the compressor is keeping the right pressure? Was having an evaporator freezing problem but I changed the dryer and it "seems" to stop that.
@@rodcleve Man, that was 50 years ago when I learned all of this. I do remember that the A6 was either on or off. Never cycling the clutch. The swash plate made the pistons move. Varying the angle of the swash changed the stroke thus decreasing or increasing the pressure but never cycling the clutch.
The most unique feature was that instead of cycling the A/C clutch on and off as in other vehicles, when things got too cold, a bypass valve routed ran Freon back into the pump rather that thru the dashboard heat exchanger. It was smoother than cycling the A/C clutch but it guzzled more gas and thus was eliminated.
In 1976 l went to GM training center just off l 75 it was basic training the dealership sponsored me, was the best yrs of my life other than my kids and grandkids
Yep we called those crotch coolers, under the steering wheel and also under the glove box for the passenger, especially appreciated in Chevrolets and Pontiacs which often had all vinyl interiors, living in a place where it gets over 100° in summer!
@@Rfk1966they weren’t the only ones… my parents Dakota and Caravan also had the interior vent which had a lever you could pull down by your left leg to let in fresh air.
I can't believe that I just spent 10 minutes watching someone play with their air conditioner controls....BUT I thoroughly enjoyed it, and the information gleened... and it was a nice 'calm-down' from my busy day! Thanks, Adam. -Greg T in California
Dad's 76 Electra 225 used that compressor. Even on the hottest days you could turn that car into a rolling meat locker. That was a fantastic AC system that most modern cars cannot measure up to.
I live in Las Vegas, we had a 75' Electra 225 and I remember freezing in the back seat, mid summer. The best modern AC I have ever felt in any recent car... SUZUKI AERIO! Yes, that dumb Suzuki has the best AC of any modern vehicle I've ever had. I don't want to daily drive my F350, diesel is too pricey.
The first time I experienced the GM bone-chill AC was my 1974 Riviera. The absolute coldest AC I ever had was my 2000 Buick LeSabre. I lived in North Carolina at the time and that thing would keep me chilled at idle on the hottest days. Unreal.
The A6 was a Frigidaire compressor & GM owned Frigidaire. Back then GM owned many companies. The a6 was good but they did have a week clutch on them. They also drain a lot of horse power but they lasted pumped a large volume & worked well. They were also used on many tractors, swathers, off road equipment.
We had an old International Harvester refrigerator in our garage. Worked great. I never should have let it go when I sold the house. It had the IH badging in front identical to their equipment. So International made a bunch of stuff too.
Your right about the clutch. I remember mine locked up on me one day and I just had to cut the belt off until I had the clutch repaired, but to me, that was a minor problem.
I have an owners manual for the 1966 Toronado, and I read where it is common for the A/C system to lose 1 lb of R-12 in a year. I also had a 1978 Cutlass Supreme with this massive A-6 compressor bolted onto the 260 V8. The rapid cool down of the R-12 A/C in the summer in central Texas is something you have to feel to believe. I had it so cold inside the car, that when I parked it, and came back in roughly 10 minutes to retrieve something from inside, the interior air condensed and turned into a dense fog. I kid you not. The outside temperature could be 100 or 105, and when the A/C compressor kicked in, those vents would blow out arctic air in the 30s within 10 seconds. That's air conditioning for you.
I had a 1980 Cutlass Supreme Brougham and had a similar experience on 105° days in So. California. The old Frigidaire R-12 systems were unbeatable. So much better than anything now.
Th A6 compressor is just great. They don't see a lot of appreciation by many enthusiasts. I'm looking to mount the original A6 compressor on my LS swap once A/C time comes around. There is just nothing better than the ice cold GM air.
The A6 compressor is great but they don't like being turned off and on like newer compressors. The newer system uses a cycle process to regulate the pressure in the evaporator. If you still have the old VIR system you can use the A6 compressor. IF you find or make the brackets it should work. Good luck!
I had a "73" Cutlass Supreme with bucket seats and console. I loved this A/C feature because it would cool the car down in a hurry. That was one awesome stylish and good driving automobile. I wish that they still used that type compressor because it was built like a tank, used R-12 and was easy to work on. Thanks for the memories of this system.
My father briefly worked as an electrical-engineer for Ford back in the early-70's...We had a 72' Lincoln & he said he was sure glad it had the GM-AC!--He quit, btw, because his manager (& good friend) told him he had to design alternator's with a limited-life-span (i.e., planned-obsolescence) to keep parts-suppliers & dealer-mechanics happy & employed (but costing customers much more & making the cars less-reliable 😢).
I am not saying it did not happen like that. The Ford starters I have are awful. And the electronic distributors from some era Fords are considered awful. But in my experience, they design the cheapest part that will last the warranty. Emissions equipment were government mandated to have a certain number of years. Parts Division at GM (and I assume the other makes) always said they make money on crash parts for cars that are new to three years old but have to sell every other part at a loss because of government regulations and warranty.
@user-wd4ev1uc8e "...no longer do they make [appliances] that *will* last..." Uh, how do you know how long a new appliance *will* last? When did they stop making appliances that do or will "last more than a few years"? Is my 8 year old fridge that works great the last one ever? Is my functional 11 year old A/C unit an anomaly? Will my 2 year old dryer expire soon?
My parents had a 1974 BMW Bavaria and a 1974 Buick Century Wagon. My brother and I as well as our sister would fight for the front seat in the Bavaria in the hope of remaining cool in the summer because the rather tepid air had become warm by the time it made it to the backseat but in the Buick we had no problem sitting in the backseat or even in the history seat because sitting up front with shorts on could be uncomfortably cold when the air conditioning was set to maximum!
Yes, my '77 Mark V has a GM compressor for the air conditioning. It's fabulous...better than any newer car I and my parents have ever owned since my Dad had the twin of my car. The heat is just as impressive...like a furnace. The system is semi-automatic vs fully automatic, where you have to make a fan selection, but the system will move the blower up and down a bit automatically when at least using the two middle fan speeds...I am forgetting if it does it on the low setting too. The highest speed just stays that way.
Great video! My 1982 Malibu Classic is still R12 and hasn't been recharged since 1994! Still blows ice cold. Interestingly, my car is an early model year car and has the A6 compressor. Had it been built later in the run, it would have had the R4 unit.
Cool feature, indeed. 😉 I’m always that so many cars in your collection have such low mileage. Unfortunately, even up market GM cars in the early ‘70s were showing poor fit and finish standards as can be seen by the poorly fitting glovebox door in this video. Thanks for the frequency of these uploads, Adam. 👍👍👍
Great overview. My 73 El Camino has same GM AC system. Too bad R12 gone, sight glass was great charge indicator and you could slightly R12 overcharge w/o issues. You mentioned these old GM systems used 4 - 5 lb R12 freon which is super cooling capacity. Cutting off heater core coolant is good for about 6-10 degree colder vent temp. Check coolant valve fail because vacuum operated diaphragm goes bad with age. Sometimes you want recirculate at less noisy lower fan speed. Maybe reason GM went to high fan speed in recirculate mode; to prevent evaporator core ice up.
GM has always had the best AC going back decades. My dad was a Ford guy when he was young and when he switched to GM he couldnt believe how cold the ac was. One of many features that sold him on GM, 40 years later and hes still 100% GM.
Maybe GM sourced the after market A/C in my parent’s AMC Matador. Even with a black interior, it took seconds to cool down on even the sweltering days of a Midwest July.
There is another system you may not be aware of. The early 70s AMC Weather Eye A/C. It had regular heater controls, but to the right was a dial that allowed you to set the cycles at the intervals most comfortable. The dial ended with a setting called "Desert Only" and would not allow the system to cycle off at any time. I live where the weather is over 100° for over a month each year, and passengers would complain how cold it got. I've read you could actually get it into the 20s or 30s, but then it would freeze the system and you would need to melt ice, which would drip on passenger feet. I have never felt anything else like it, and have owned GM cars, too.
AMC used GM Frigidaire components to build AC systems for their cars. Like most all did the same. GM traded under many brand names around the world.. 💯 🇺🇸 Trump 2024 🇺🇸
If I recall, that compressor had variable capacity based on heat load. There was a swash plate unloader mechanism modulated by refrigerant pressure. This ensured greater comfort when running air conditioning. The only purpose of the clutch was to engage the compressor when selecting air conditioning. The later short compressors used the magnetic clutch to cycle the compressor as controlled by the pressure switch resulting in a less refined load match.
Not the A6, it had fixed swash plate. The use of a POA valve in suction line that would take the overflow of higher speed and still get oil back to compressor when exp valve flow was reduced for a cooled interior/low fan speed and refrigerant flow was least.
@@jimmyaber5920 Great info! What happens when a POA valve eliminator and corresponding expansion valve is used when converting to R134a. Is it doing the same job as the original POA valve but just set for r134a evaporator pressure?
The CCOT system. Had a 4 cylinder Phoenix in the 80's with that system which worked well and was much simpler but the cycling of the AC clutch was annoying -the engine would buck and surge when the AC was set to low cool.
GM air conditioning was the best by far, I grew up in a state where often it would get over 100° in the summertime and those 70s cars with real metal Chrome could get very hot to the touch, and I remember in just a few minutes and frigid cold air would come out of those vents and it was amazing! Typical GM to take something they had perfected and made world-class and then ruin it, there were SO many other ways to save weight or increase efficiency in their cars rather than getting rid of one of the things that really was the standard of the world. Also, I remember being in a less popular (possibly off brand car) that actually would sometimes blow snowflakes out of the vents, maybe it was faulty in some way but it sure was refreshing on those very hot and humid 90 degree nights! lol
@@psymi-hk1fp we "upgraded" to an 85 LeSabre... with a V6... from that 72 Caprice 400ci... Although the Buick had tufted velour power seats etc, what a step DOWN. The ac was of course, far inferior. And it has to be driven in "low drive" most of the time because "regular drive" clanked in and out of overdrive so much it sounded, and felt, damaging. It LOOKED good for the time, much like your Electra, like contemporary more expensive Olds/Caddys, but what a hunk of coal otherwise. My folks, who had owned large GM domestics from the 1950s forward, always missed that 72 Caprice. (61 Impala a close second.) The 1992 Caprice 305 is nice (and still runs at over 200k), but just can't match that ride and effortless power of the 72 Caprice. And the "new" 92 ac NEVER cooled as well, even when new, on full blast, nonstop. Sigh...
The GM cars we owned back in the day did not have this feature. The '70 Buick Estate Wagon had a separate setting for recirc called "max" for A/C. The '80 Oldsmobile had A/C settings of "max" "norm" and something called "bi-level". On both cars you could actually run the A/C on max and adjust the blend door to your preferred temperature. This had the benefit of keeping dirty outside air out of the car. During the old smog days this was helpful. But you could only use this selection for A/C. I remember this feature and as a driver today on my new Toyota I choose to recirc air because of the pollution. On the new car it's a button that can be used on all settings except for defrost. On occasion my new car thinks its smarter than me and reverts to fresh. I smell the exhaust and then have to re-engage the button. I like the new car but still prefer the setup on the '70 Buick. It's easier and does what it's told. Fun story - In the summer back in the day as a 16 year old I would get the Buick to the State highway intersection, turn east and punch it. With the A/C on. The car would hammer to 60 leaving a huge brown cloud of unburnt hydrocarbons on the highway, my 120lb frame smashed to the back of the drivers seat as if I was a 250lb man. I remember my cousin riding along looked at me and said "455 don't care."
Both my Honda and my Hyundai fight with me if I try to use the defogger in recirculation mode, but they give in if I keep hitting the button. The setting is useful when trying to get the ice off the windshield fast, but it does risk fogging up the windows while underway.
Very nice, our old Buick Electra had a control like you showed with the Recirc marked and yes it was Arctic cold even in summer 😅. I also loved the old AMCs with the “Desert Only” Weather Eye setting, it kept the compressor on all the time but I don’t know if it also triggered recirculate or a higher fan speed.
R12. Good stuff. In the 90's the government made it impossible for a DYI'r to buy R12. So, I took an online class and got a certificate that allowed me to buy R12. I bought a 20 lb canister of it. I still have it. I would use it every 4 or 5 years to top off my 1977 Regal, 1975 Park Avenue and 1978 Eldorado. The AC in these cars was terrific but I never liked the automatic AC because in Florida you just can't get it cold enough. The recirculation feature was I beleive not available on that system. The Regal had manual AC with recirculate and it was great but the cabin was smaller too. Good video.
So glad by the 90s, most vehicles had a separate A/C button to kick on the compressor and a seperste recirc button. Can't believe it took everyone that long to figure it out.
I think the reason the system would only blow on high in the recirculation/Max position was to prevent the evaporator from icing up . This was particularly a problem in the expansion valve type systems in humid conditions as is common in Florida. It was common for Fords and Chryslers to ice up on long trips because the system would be left on recirculate. Even if the fan was switched on med or low it's less likely to happen with those that have the orifice tube systems or any system that cycles the compressor. I think the elimination of that feature coincided with the introduction of the cycling compressor.. Although the expansion valve was supposed to prevent icing, it wouldn't do it so well at low blower speeds in recirculation position. It wouldn't be as apt to freeze when warmer outside air was blowing across the evaporator .
I wonder. A late uncle of mine who was one of the few "car guys" in the family owned a '76 or so Grand Prix which had the later AC control layout with MAX/Normal/Bi-Level AC settings and no forced high-speed blower setting on full cold, and if that car's AC was run on MAX for enough time with the blower at a lower setting the evaporator would freeze up until no air would flow through the vents, and the ice on the low-side line under the hood was as thick as a baseball bat with ice! :D So then he'd just set it to vent and let it defrost before switching back to AC. Memories sitting in the middle of the front seat of that car in the mid-late 70's between my uncle and dad on a family vacation trip where by being stuck in the middle seat I had control of the AC and the AM/FM stereo radio which was not so common an option back then! Dearly miss my uncle and also miss that Grand Prix, he let my dad drive it and dad said it was the best car he'd ever driven at the time.
@@terrybeavan4264 I think many of us have similar childhood memories of sitting in the middle seat. Today’s kids will never know because no cars have a space for a middle passenger in the front seat anymore. Unfortunately, although it’s a lot less common due to various temperature sensors , the icing issue hasn’t been completely solved even today, especially on longer trips in humid regions.
Im a mechanic and specialize in ac repairs. Been doing it for roughly 13 years. Chevrolet has the coldest ac ever. Especially the 80s when they were leaving r12. They hit it on the head and government made them seitch to 134a
Charles Kettering of AC Delco GM invented freon AC and electric start auto electric for cars trucks. Also He invented first Diesel electric Train Zephyr and Detroit diesel two stroke diesel. Look up "Kettering Sperry Bug " first aircraft drone made after ww1 .
I absolutely remember that odd setting of the temp lever to the extreme left to obtain the recirculating or Max setting of the A/C on my parent’s 1974 Chevrolet Monte Carlo. It was a great looking car but turned out to be a lemon. Too many issues to describe here. After 3 years, they traded it in for a new 1977 Buick Regal Landau. That car was a beauty and had excellent quality control. Thanks for all of your videos on all the various makes and models of cars. I look forward to them everyday!
As I recall, the recirculation "fan" always ran even in the off mode. The other thing about the Oldsmobile rocket engines is that when the heat was on especially in vent mode, they had a very distinct aroma. Now that I'm thinking about it, my 1979 Park Avenue Coupe had the Olds 403 6.6-liter engine. It also had the Oldsmobile distinct odor!
The owners manual for my 75 Firebird states the fan is designed to run even in the off position to keep air moving through the damp AC unit to prevent mold and mildew......it also created a nice chilly draft under the dash in the winter however it could be switched to an annoying hot wind on your knees.......anything but completely off even if the car was comfortable without using the heat/ac.
My 01 Malibu and my buddies 98 Silverado both would let air flow through at highway speeds. The fan was off but you could definitely feel warm or cool air flowing through depending on where the temperature was set
@@imthemistermaster I have always heard this was a deliberate safety thing, as it means there is always fresh air entry to the car when in motion. Probably more that they didnt see a need to install a damper to totally close off the system when its off since very few people shut the HVAC on a car totally off. I usually ran vent mode if I did not need a specific thing for example.
The weirdest quirk I know of in GM HVAC is that you can't turn the fan to actual "OFF". I've _never_ had a GM that would actually shut the blower down. It's really fun when the bearings start to fail in the blowers and you get the tell tale rraaarrarwwwrrrrrrrr which cannot be stopped. 😂
The fan however had a thermal switch in the circuit to kill the fan when the-in car temperature was below 40 degrees and the slider was in the off position. This eliminated cold air discomfort in the winter during cold startups.
many later cars had that "always on low" fan feature, but if the system was turned off, the fan was actually off. (depending on the make) MOPAR had the low fan deal that was on any time the HVAC was on, although you could defeat it by slightly pulling out on the heat button. (button system, not sliders) I was aware of this issue on late 60s full size vehicles because people complained of the excess draft or overheating in the passenger area. I guess they were too lazy to move the temp lever.
In my opinion the compressor you show here and Chryslers V twin compressors were the best that were ever used in automotive air conditioning. I’m retired from HVACR field after forty seven years I never did any automotive air conditioning except for my own and family. I really liked those two compressors they seemed to run forever and would take more abuse than today’s compressors. It’s the same way in the field I was in.
I never tried it but I’ve seen it done. It’s a shame when America has something so good on the market that they have to stop manufacturing it because it doesn’t break down and make them money. 😡🤬
@@jamesgizasson Same here, everything I own is old but it’s paid for and still works while everyone else is in debt for buying junk they don’t even own anymore. They have to buy new junk 🤣
@@czechmate6916Yeah. I used to hate modern cars because they were so expensive and complicated. Now I hate them because I know that all that money doesn't actually buy you a better car... just a prettier one.
A couple of years ago I was melting while picking up a friend's kid from school. Long line, pull up 2' at a time, blazing hot parking lot, no shade--like a traffic jam. I had a new Honda Fit, huge windshield, sunroof w/shade closed and AC on full blast. Nothing. I was like--Really?? Are the summers this much hotter? No, it's just not an old GM unit.
'60s/early '70s MoPar and mid-'70s-up GMs have just AWESOME air conditioning. I don't think anyone's ever done it better. If it's not hot and in the daytime, the old GMs I had and my '67 Belvedere's temperature setting would rarely be more than like 1/8" toward the 'cool' end of center, and I almost never turned the fan above the first or second setting, usually in defog/floor. Max AC/recirc was strictly an 85°+ with the sun out situation.
@@psymi-hk1fp My '80s Buick Regals remain the most impressive vehicles I've ever been in to this day with regard to AC frigidity. There was something wrong with yours, I can say that with 100% confidence.
I actually met the guy that designed the AC for my Olds Achieva (97) at a gas stop in Georgia in August, he asked how I liked it? I told him I knew when the turkey was done in minutes! That was the best AC I’ve ever had in any car I’ve ever owned!! My Pontiac wagon (73) was amazing too!
When I went to GM Training Center in 1973, they taught us to rebuild the A6 compressor with Vaseline because it had low melting point and would mix with the compressor oil.
I have a ‘63 Sedan deVille w/AC. That car is now 60 yrs. old. I’ve owned it since 1980. It still blows ice cold and always has. I have never had to add refrigerant. It does NOT have a recirc feature at all as far as I know. I’ve also had a ‘73 Fleetwood Brougham d’Elegance (60 Special) and a ‘75 Buick Electra Limited Park Ave. These cars both had the recirc position as you’re showing on your olds. I’m presuming that they had the Compressor that is the subject of this video. While they both did speed up the fan and switch the position of the mixer door. But they also leaked out. I had to add refrigerant just about every season. As to other makes - I’ve had 9 Chrysler Mini-Vans. 8 of which had AC. They all had a recirc button which sped up the fan. However several of them quit working at the higher speed after some time!!
GM is well known for their A/C, at least they used to be. I grew up in the back seat of my Mom’s ‘84 Park Avenue and she kept a blanket in the back seat for long road trips. I think only Toyota tops them for A/C. My cousin had a late ‘80’s Camry and that thing could blow ice cubes even with its 4 cylinder engine.
The only way I can get Recirc / Max AC in my 1994 Cadillac is to set the temperature on the digital display to 60 degrees. When set to 60 degrees the air is recirculated and the blower automatically goes to maximum speed. What sucks about this car is that there is no way to select bi level air conditioning.
My first car a 1975 Ltd had this fridgedaire system on it with an expansion valve which kept the compressor on constantly so you didn’t feel kick off and on all the time and it all these years later was hands down the best ac system Ive had and im a ford guy. I’ve been mechanicing almost 40 years. Time flies
I remember this feature very well, it caused a return to the dealer early on when the parents first got the 73 Caprice coupe. Needless to say, they had the temp lever all the way to the left so the fan was on high when in AC mode. Our 69 Caprice had a separate position on the control lever for the recirc AC mode. No problems once the operation/control was explained to them. I have to comment that this control was super easy to use, everything could be controlled by "feel", provided you remembered the relative detent positioning on the top control mode lever. Funny that you mention the heater core hose control valve, I don't think the 73 Caprice had one of these.... The only reason I remember/noticed is because I changed the heater core/heater hoses so many years ago and would have remembered a valve like that. Peculiar features do get replicated though. Believe it or not, my 09 Camry has a similar control feature. Turn the temp knob all the way to cold engages the AC recirc mode and a higher fan speed! This feature is ever more frustrating on my Camry because it acts like a switch to turn the AC on even though the AC switch might be off. The temp control knob must be turned away from this position before the AC will shut off. Needless to say, this foolish design flaw has resulted in some colorful commentary by yours truly. For my money, the HVAC control on the old Chevy (no comfortron) was great. You could make any adjustments to the system without having to look at the controls, or some idiotic screen.
What you say is true, and 100% your experience. I like these controls, simply because it was ubiquitous. Everyone had a GM, and if you drove another's car you could figure it out instantly. That doesn't make it the best. Honda climate controls had all the same features with 3 dials, and they kept the same design in every model. expensive or cheap. Again, the same easy to operate and the dials, for me are easier to work with no look.
@@fleetwin1 O, was I mad when Toyota and Honda went to touchscreens. Like every other car company. Wanted them to fight the power and keep it as simple as possible. Nice to hear a nice comment from a nice YT viewer.
Sounds like that blower motor needs a rebuild! I was sure you were going to discuss the flow-through ventilation on the early ‘70s GM cars, with the louvres in the trunk lid to enhance ventilation.
My dad had a '69 Buick Wildcat with that deep-freeze compressor. It could be over 100 degrees outside, and the inside of the car would be like a meat locker.
The '70s. Where GM took an Air Conditioning system and built a car around it. 😂 Seriously, in February of 1988, I bought a 1976 Oldsmobile Cutlass. The A/C still worked perfectly. 12-year-old A/C that could damn near freeze you out of the car on a hot summer's day. Glorious stuff!!
GM really had the best air-conditioning. I really back in 79, my Boss drove a Mercedes and he went somewhere with friends and they had a Cadillac and he commented how nice the Air was,
I feel like early late 80s- early 2000s Fords had a similar setting but it’s with a dial. Panel setting turns off A/C, upper vents, blows outside air A/C turns on A/C, upper vents, blows outside air MAX A/C recirculates air, upper vents, and high fan speed(maybe others) has more blower motor power than any of the other settings on the dial.
I had a 1979 Ford Thunderbird with an Eaton compressor and I had a 1979 Ford LTD with the A-6 Frigidaire compressor. Both cars had good air conditioning and I never had an issue with the Eaton compressor. That A-6 IIRC had the compressor clutch mounted in rubber on some of the later models and it came apart on the way home one night. My dad had an A-6 from a 1967 Buick Electra under the work bench and we pulled the compressor clutch off that and it fit perfect. I drove that car 200,000 miles and it was still blowing cold. GREAT VIDEO!
Come to think of it, in my 2016 Camry, if you turn the temperature knob all the way into the blue zone it puts the system into recirculating mode, despite the fact that the HVAC panel has a dedicated Recirc button. But turning the knob all the way into the blue zone has no effect on blower speed.
Love this! I don't remember you featuring this car on UA-cam, but those Cutlass cars were a sweet design that circumvented the Nader bumpers so well. Thanks for sharing!
I'd recognize that 1975 Olds Cutlass dashboard every time! Few years back we sold dad's original 1975, 12k mile red w/white stripe, 455/th400 car he ordered new from charnock olds here in Dearborn. It went to a good new home.
😆 As a kid in the 70s and driving teen in the 80's with a family that was up until that point almost exclusively GM, I always thought the GM air conditioning controls were the most ridiculous and non-intuitive systems ever created. Now I know why...(sorta!) I was so appreciative when I finally bought an old used Mazda and the climate control system actually made sense (ie, controls for 1-fan speed, 2-temperature, 3-AC compressor on/off, 4-recirc, 5-vents used). Thanks for the memories! 👍
I love those GM A6 axial compressors. They were big and heavy, and it took a lot of power to run them. But they worked. And they lasted. The Harrison compressor that followed was complete junk. They were often called pancake compressors due to there design, and you could count on them failing every 2-3 years. They almost always started leaking where the end caps were welded to the body. They were very flimsy. They used a lot less power to run, and that may have been the reason why GM switched to them. I have a 1976 Corvette with the A6 compressor, and it will freeze you out. That control design is similar to more modern designs that use "MAX A/C" to get more air, and use recirculated air rather than warmer outside air. I have a 2006 Mercury Grand Marquis, and it has a real nightmare of a climate control system. It uses constant flow of hot coolant through the heater core, and has a "blend door" to mix hot air and cold air to give you the temperature you want. The big issue with this system is the "blend door actuator" a small cheap plastic box with a tiny 12V motor and cheap flimsy plastic gears in it. These things inevitably fail after a short time, and their location makes it necessary to remove most of the dash to replace them. Mine failed. After doing some research, I found that I could remove the passenger side airbag, fabricate a chisel out of a 20" piece of rebar, and get it back in there far enough to break off the corners of the blend door actuator where the attachment screws went, and move it away from the bellcrank on the blend door. I was able to jam the blend door into the full A/C position. I also removed and plugged the heater hoses to keep coolant out of the heater core. I live in Phoenix, AZ, where summer temperatures average 110-112 degrees F, and it never gets cold enough in the "winter" where a jacket won't keep you warm. This nightmare could have been avoided if only they had used wire cables to move the blend door. They tend to last forever.
I had a few Panther cars and that blend door actuator motor is a common failure point. The good news is that it's possible to replace it by just pulling the glove box and the passenger side airbag. You only need to destroy one corner bolt as I recall. It's not *easy*, but it beats trying to pull the whole damned dashboard out.
I always found the 80s to early 90s slider HVAC controls in GM products quite confusing as a kid on what was supposed to perform what function. The unit Chrysler used in the early 90s k based vehicles took no time at all to figure out with its visual directional diagrams assigned to a single button, button specifically for air conditioning, and a slot for recirculating.
When I saw the video title I knew what you were talking about. Its true what other commentators have said these were the coldest A/C systems ever put in cars. Had one in a 73 GTO in New Orleans and it would freeze you out after a few minutes in that mode.
It did not go away. That is 5:43 simply max AC on almost every vehicle on the road today with AC. I can’t believe you find it amazing when it’s a standard feature everywhere.
I had several Olds mobiles during that era, including a 73 Cutlass. The A/Ć control with the MAX detent was for hot humid climates like deep south and mid west. As it was explained in my Owners manual, initial startup in hot car meant rolling down the windows, start engine, put cooling on the system on "MAX COOL" setting, anf be careful about touching hot interior surfaces. As driving time accumulated we began rolling windows up until the two front ones were open 2 inches. This allowed maximum cooling effect and helped to quick flush the hot air out. The, once the windows were shut, reduce cooling switch to Normal setting and enjoy the ride.
I remember that my 77 Pontiac LeMans would set the fan to Hi whenever I switched the control to “Max A/C” this was a new experience for me. It was a good A/C system especially with that R-12 which at that time was $2 a can at K-Mart.
I agree with your description of the fan speed increase on recirc (since you can clearly hear the fan noise pitch increase) but am reminded of a car-nerd debate I got in with a Honda owner, who thought the same was happening on their 1990 Prelude. Another independent noise effect also occurs when a car's HVAC is switched to recirc - the passenger cabin becomes exposed to the inlet-radiated noise of the ventilation fan, which can make the fan a lot noisier (even though it is not passing any more air, nor has its pitch changed).
I knew instantly what you were going to talk about when you mentioned "GM only". I believe I first saw that on the 71 GM cars. And, it was a feature that I hated! There are a number of times where you might want the A/C in the recirc mode, without the hi blower speed. Had I owned a car like that, I would have immediately rewired it. On the other hand, that A6 compressor was considered to be the best compressor ever, because it was smooth, quiet, and lasted forever. However, it weighed a ton, and needed a fair amount of horsepower to run it. What is funny is that GM went from having the best A/C in the world, to having the worst, once GM went to the horrible R4 Harrison compressor.
I switched the vacuum lines in my '86 Dodge Lancer so that it would always be in recirculation mode. Before that, it only recirculated when the slider was at the coldest setting, so if you wanted it cool but not freezing, you got clammy outside air.
1. That a a real clean looking under hood. Looks beautiful. 2. I had a 1962 Olds Dynamic 88 and the A/C vents on the dash were metal balls chrome plated. It would get so cold that frost would form on the vents.
I recall talking about these systems while at GM school in the mid 70s and I believe they were almost 2 tons of AC with a bottom line of about 38-42 degrees air temp at the center vent, which was quite a bit lower than other makes of the era. Heck, these days my 2014 Dodge is hard pressed to go much below 50 degrees unless it's an overcast / rainy day. BTW, not sure when GM went to using barrier style AC hoses but was told by many the R-134a conversions can leak right through the rubber on the older style. Have done a few conversions on 80s vintage with few problems there. The GM systems had enough extra capacity to deal with the slightly less efficient 134a. Not so an all other systems. I also still have a couple of one pound cans of R-12 in case I stumble on an older system that needs a top up. Makes me wonder what else is in the back of my garage, eh?
I own a 1975 Cadillac Eldorado, and the system is quite similar to this one, A6 compressor, VIR diverter valve, and also is equipped with automatic temperature selector wheel in the control panel and with a "computer controlled" 😀module under the dash to select the vents, temperature and fan speed. All working flawlessly like the first day.
Back in the 90’s, my boss said a lot of good things about GM air conditioning systems. I watched a mechanic rebuild a compressor once and I believe it was a GM automobile that he was working on.
I drove an International cabover 943,000 miles, owned by Ryder truck rental, every 200,000 miles the R-6 compressor would give out, I’d be close to a “Ryder Service Center” , pull in and get a “re-manufactured” R6 compressor @ receiver dryer changed out. We ran Ca = west & Fla = east year round. The re-man compressors lasted as long as the new unit did. Very dependable in hot summers in the southern states
Yep - in the Texas summer, those GM air conditioner units worked great! The controls provided practical function, but I absolutely hated not having independent manual control. Good thing those barges took all the joy out of driving and it was just an appliance - that was well suited to the Texas driving conditions.
In 1973 I had a Mercury Montego company car (very plain...Inspector Erskine from the old "FBI" series rode around in versions like mine). The AC system had the same slider set up wherein sliding it all the way to the left engaged the recirc mode. The doors and baffles were vacuum controlled. I was working in Fresno in sales at the time and was amazed how well the piston compressor pulled the temperature down to very cold while idling in a parking lot while i did my paperwork on the fly. Growing up in a Ford family (and being a car nut) I was very aware of GM's superior rotary compressors and VERY annoyed at Ford's rumbly piston compressors. My parents years later bought a Mercury Monarch that came with the GM 6 compressor. I now understand why we could never use the fresh air setting of the AC: The heater door obviously was not closing all the way in the coldest setting before the detent, so hot air was bleeding into the air flow. The only way we could have that GM cold blast was on full recirc with the temp lever all the way to the left. Also, the GM compressor flung oil all over the engine compartment. At the time I was convinced GM was selling Ford defective compressors on purpose. I never understood why in the early 70's they unnecessarily complicated the climate controls...the Max/Norm/Vent options were perfect for setting the climate just the way you wanted...quickly. Thanks for covering this aspect of GM's designs
My uncle, a Chevy dealer at that time, sold his demo car to my family. The climate control had a temp setting and a sensor on the dash. Set and forget. WAY ahead of its time.
My '75 Monte Carlo had the same setup. Farthest left was MAX air, and then one step in allowed the fan controls to be set. I think by '76 they went to the MAX, NORM, BI-LEVEL setting on the top slider.
Very good reminiscing on old gm ac systems. I clicked on this vid, thinking it was about their insanely frustrating electronic climate control systems. I believe it was called comfortron in their hi end vehicles.
with the older R-12 system, I was taught to perform a pressure test to see if it would hold, after a few days if the pressure held you'd then vacuum it down as far as it would go and let all the moisture boil off. Finally, after all that you could then charge it.
We had a 77 Caprice when I was a kid. It had 'max' and 'normal', but anytime Max was selected the fan speed automatically went to high. I also remember the weird Ford/Lincoln setup back then. They had a Hi-Lo setting that would alternate airflow from the upper vents to the lower vents. Back and forth. I doubt very many people ever used it.
Our family's 1976 Oldsmobile Custom Cruiser had the A6 compressor with the "tempmatic" AC, you'd set the temperature and the system took care of the rest, including fan speed. It was awesome. If set manually, it had that detent to increase fan speed as well.
Back in ‘70’s I detailed cars during summer. One regular had a Rolls Royce with a GM A/C system. One hot day he asked me to look at his car to see why the A/C wasn’t delivering cool air. I figured out the condensation on the backside of his metal dash vents had frozen shut. Rolled them over, let it thaw, AOK.
My family's 1976 Cadillac Eldorado Biarritz had the "climate control" on the left hand side of the steering wheel. The thing had a wheel to adjust temp and a bi level basically meaning "in your face and down to the floor" cold air. When you saw an ad for a 70s Chevy advertising "air blows ice cold" they mean it! Chevy really knew how to make an industrial grade ac for an automobile. It's cold, better than most HVAC home units at the time, and used that toxic Freon 12 (pre 134A conversion) but it sure could cool a car. And Cadillac made sure you were comfortable in the often named "Queen Mary or Titanic". Looked like a land yacht, ran like a land yacht with air ride suspension, and kept you warm and cool in sumptuous leather and HUGE power seats. Chevy and it's GM associate brand (Pontiac, Oldsmobile, Buick) really make their cars unique and each is special in its own way. I miss the days of charm and character in cars.
Modern GM vehicles (without auto climate control) work similarly. On my 2018 Cruze for instance... When the AC is on and you turn the hot/cold dial into that final notch all the way cold, it engages recirculation (if you haven't already selected recirc with the separate recirculate button). I don't think the fan speed actually increases, but it sounds like it does since recirculate mode always makes the fan sound slightly louder.
I can remember my dad taking an old air compressor from an air conditioning unit and I believe it was GM and I believe it was frigidaire. It was an upright almost looks like a small go-kart engine. He built a small frame and hooked up a washing machine or dryer motor. He braided on the output side an air hose. And said here you go this is what you use to every bicycle tires. You know I use that and still have it.
The Comfortron system was even cooler. It was thermostatically controlled and would automatically switch from heat to cooling as you drove as weather conditions varied.
Having owned many 1971-1976 GM cars, I believe the introduction of this feature coincided with the Forced Ventilation system with the fan that continued to run on low when the system was turned off. Both features were designed to positively pressurize the passenger compartment to prevent carbon monoxide buildup in the event of an exhaust leak. Recirculation mode still had a small percentage of outside inducted, but this was enough in terms of volume as the fan speed would be on mandatory high.
That doesn't seem right because on max air it would recirculate the inside air. Recirculate did not add any outside air. I worked on vehicle ac in the 1970s
I read this someplace credible at the time, quite likely at least one of the owner's or shop manuals from the multiple 1971-76 GM cars I have owned. It makes sense given the engineering emphasis of the systems, but I have no way to know how to confirm it, or if the divisions were given a choice in the matter (I would suspect not).
Three guys from Brooklyn invented car air conditioning....Max, Norm and Hi
Then they walked into a bar…..
🤣😂😂🤣
Yeah, I remember them. They had a cousin named Bi Level. Nice guys, really cool.
@@MyHumanWreckageBi level was a good friend of my dads
Bi Level was hot and cool.
Sometimes he needed to vent.😅
My friend Def Rost could melt the ice in any social situation.
I went to GM air conditioning school in the early 70's. Those compressors were 6 cylinders where others were 2 cylinders. They did not use a cycling clutch as most others. They had 3 sets of 2 pistons controlled by a swash plate and kept the pressures correct. Some also were controlled by a thermostat dial which turned on heat or ac or blend to keep the temp correct. No electronics, all mechanical. Great system.
That's great info! I wasn't aware the A6 compressors kept the pressure correct. I'm learning as I go about these systems. My GM car is R134a converted with a POA valve eliminator. I wish I kept the old POA valve and used the screw/bolt to adjust evaporator pressure for r134a. I'm not having any problems with the POA eliminantor but the compressor never goes off. Is this because the compressor is keeping the right pressure? Was having an evaporator freezing problem but I changed the dryer and it "seems" to stop that.
@@rodcleve Man, that was 50 years ago when I learned all of this. I do remember that the A6 was either on or off. Never cycling the clutch. The swash plate made the pistons move. Varying the angle of the swash changed the stroke thus decreasing or increasing the pressure but never cycling the clutch.
They basically worked the same as a hydrostatic pump.
The most unique feature was that instead of cycling the A/C clutch on and off as in other vehicles, when things got too cold, a bypass valve routed ran Freon back into the pump rather that thru the dashboard heat exchanger. It was smoother than cycling the A/C clutch but it guzzled more gas and thus was eliminated.
In 1976 l went to GM training center just off l 75 it was basic training the dealership sponsored me, was the best yrs of my life other than my kids and grandkids
Most GM vehicles had a vent under the steering column or what we called the ball cooler lol
The old crotch vent….Toyota still had them in the 90’s
Yep we called those crotch coolers, under the steering wheel and also under the glove box for the passenger, especially appreciated in Chevrolets and Pontiacs which often had all vinyl interiors, living in a place where it gets over 100° in summer!
Yep a barrel vent
@@Rfk1966they weren’t the only ones… my parents Dakota and Caravan also had the interior vent which had a lever you could pull down by your left leg to let in fresh air.
@@Rfk1966I love the ball cooler in my 80 series Landcruiser
I can't believe that I just spent 10 minutes watching someone play with their air conditioner controls....BUT I thoroughly enjoyed it, and the information gleened... and it was a nice 'calm-down' from my busy day! Thanks, Adam.
-Greg T in California
Dad's 76 Electra 225 used that compressor. Even on the hottest days you could turn that car into a rolling meat locker. That was a fantastic AC system that most modern cars cannot measure up to.
In that case the only thing missing was the meat hooks! 😂
I live in Las Vegas, we had a 75' Electra 225 and I remember freezing in the back seat, mid summer.
The best modern AC I have ever felt in any recent car... SUZUKI AERIO!
Yes, that dumb Suzuki has the best AC of any modern vehicle I've ever had. I don't want to daily drive my F350, diesel is too pricey.
Good old R12
Never took much to get an old gm to have cold air
Back then they used Freon (R12) as the refrigerant. That R134a substitute they use now doesn't come close to it...
The first time I experienced the GM bone-chill AC was my 1974 Riviera. The absolute coldest AC I ever had was my 2000 Buick LeSabre. I lived in North Carolina at the time and that thing would keep me chilled at idle on the hottest days. Unreal.
Beautiful car, 70s one of my favorites, the Riviera!
The A6 was a Frigidaire compressor & GM owned Frigidaire. Back then GM owned many companies. The a6 was good but they did have a week clutch on them. They also drain a lot of horse power but they lasted pumped a large volume & worked well. They were also used on many tractors, swathers, off road equipment.
We had an old International Harvester refrigerator in our garage. Worked great. I never should have let it go when I sold the house.
It had the IH badging in front identical to their equipment.
So International made a bunch of stuff too.
Your right about the clutch. I remember mine locked up on me one day and I just had to cut the belt off until I had the clutch repaired, but to me, that was a minor problem.
Frigidaire? French company???
@@SuperMixedd It was founded in Ft. Wayne Indiana in 1918. So no, not French.
@@TheBandit7613 oh my i always thought it was french lol
The sight glass...man I had completely forgotten about that. Thanks for the reminder.
I have an owners manual for the 1966 Toronado, and I read where it is common for the A/C system to lose 1 lb of R-12 in a year. I also had a 1978 Cutlass Supreme with this massive A-6 compressor bolted onto the 260 V8. The rapid cool down of the R-12 A/C in the summer in central Texas is something you have to feel to believe. I had it so cold inside the car, that when I parked it, and came back in roughly 10 minutes to retrieve something from inside, the interior air condensed and turned into a dense fog. I kid you not. The outside temperature could be 100 or 105, and when the A/C compressor kicked in, those vents would blow out arctic air in the 30s within 10 seconds. That's air conditioning for you.
I had a 1980 Cutlass Supreme Brougham and had a similar experience on 105° days in So. California. The old Frigidaire R-12 systems were unbeatable. So much better than anything now.
@@michaelmullard4292 todays AC cools the car a respectable 30-40 degrees (at a generous absolute most.) To my knowledge
Th A6 compressor is just great. They don't see a lot of appreciation by many enthusiasts. I'm looking to mount the original A6 compressor on my LS swap once A/C time comes around. There is just nothing better than the ice cold GM air.
The A6 compressor is great but they don't like being turned off and on like newer compressors. The newer system uses a cycle process to regulate the pressure in the evaporator. If you still have the old VIR system you can use the A6 compressor. IF you find or make the brackets it should work. Good luck!
I'd agree A6 doesn't "like it" but they were OE configured as "clutch slammers" on a few applications.
I had a "73" Cutlass Supreme with bucket seats and console. I loved this A/C feature because it would cool the car down in a hurry. That was one awesome stylish and good driving automobile. I wish that they still used that type compressor because it was built like a tank, used R-12 and was easy to work on. Thanks for the memories of this system.
I also had a 1973 Cutlass Supreme coupe that I bought new. Loved that car (and the A/C system) and would like to find another one in mint condition.
My father briefly worked as an electrical-engineer for Ford back in the early-70's...We had a 72' Lincoln & he said he was sure glad it had the GM-AC!--He quit, btw, because his manager (& good friend) told him he had to design alternator's with a limited-life-span (i.e., planned-obsolescence) to keep parts-suppliers & dealer-mechanics happy & employed (but costing customers much more & making the cars less-reliable 😢).
I am not saying it did not happen like that. The Ford starters I have are awful. And the electronic distributors from some era Fords are considered awful.
But in my experience, they design the cheapest part that will last the warranty. Emissions equipment were government mandated to have a certain number of years.
Parts Division at GM (and I assume the other makes) always said they make money on crash parts for cars that are new to three years old but have to sell every other part at a loss because of government regulations and warranty.
Designing a part with planned obsolescence to keep parts-suppliers happy is the opposite of how obsolescence works 🤣 stupid
I'm sure that's what they told him😂😂😂😂
@user-wd4ev1uc8e "...no longer do they make [appliances] that *will* last..."
Uh, how do you know how long a new appliance *will* last? When did they stop making appliances that do or will "last more than a few years"? Is my 8 year old fridge that works great the last one ever? Is my functional 11 year old A/C unit an anomaly? Will my 2 year old dryer expire soon?
My parents had a 1974 BMW Bavaria and a 1974 Buick Century Wagon.
My brother and I as well as our sister would fight for the front seat in the Bavaria in the hope of remaining cool in the summer because the rather tepid air had become warm by the time it made it to the backseat but in the Buick we had no problem sitting in the backseat or even in the history seat because sitting up front with shorts on could be uncomfortably cold when the air conditioning was set to maximum!
We have 2014 BMW and the A/C is not great!
Yes, my '77 Mark V has a GM compressor for the air conditioning. It's fabulous...better than any newer car I and my parents have ever owned since my Dad had the twin of my car. The heat is just as impressive...like a furnace. The system is semi-automatic vs fully automatic, where you have to make a fan selection, but the system will move the blower up and down a bit automatically when at least using the two middle fan speeds...I am forgetting if it does it on the low setting too. The highest speed just stays that way.
Great video! My 1982 Malibu Classic is still R12 and hasn't been recharged since 1994! Still blows ice cold. Interestingly, my car is an early model year car and has the A6 compressor. Had it been built later in the run, it would have had the R4 unit.
Cool feature, indeed. 😉 I’m always that so many cars in your collection have such low mileage. Unfortunately, even up market GM cars in the early ‘70s were showing poor fit and finish standards as can be seen by the poorly fitting glovebox door in this video. Thanks for the frequency of these uploads, Adam. 👍👍👍
Educational and informative. Thank you Adam.
Great overview. My 73 El Camino has same GM AC system. Too bad R12 gone, sight glass was great charge indicator and you could slightly R12 overcharge w/o issues. You mentioned these old GM systems used 4 - 5 lb R12 freon which is super cooling capacity. Cutting off heater core coolant is good for about 6-10 degree colder vent temp. Check coolant valve fail because vacuum operated diaphragm goes bad with age. Sometimes you want recirculate at less noisy lower fan speed. Maybe reason GM went to high fan speed in recirculate mode; to prevent evaporator core ice up.
GM has always had the best AC going back decades. My dad was a Ford guy when he was young and when he switched to GM he couldnt believe how cold the ac was. One of many features that sold him on GM, 40 years later and hes still 100% GM.
Maybe GM sourced the after market A/C in my parent’s AMC Matador. Even with a black interior, it took seconds to cool down on even the sweltering days of a Midwest July.
There is another system you may not be aware of.
The early 70s AMC Weather Eye A/C. It had regular heater controls, but to the right was a dial that allowed you to set the cycles at the intervals most comfortable. The dial ended with a setting called "Desert Only" and would not allow the system to cycle off at any time. I live where the weather is over 100° for over a month each year, and passengers would complain how cold it got. I've read you could actually get it into the 20s or 30s, but then it would freeze the system and you would need to melt ice, which would drip on passenger feet.
I have never felt anything else like it, and have owned GM cars, too.
Desert Mode is epic. I miss the old AMC cars, it's a shame they went out of business.
AMC used GM Frigidaire components to build AC systems for their cars. Like most all did the same. GM traded under many brand names around the world.. 💯
🇺🇸 Trump 2024 🇺🇸
Best AC system in any car I ever owned was in my '78 Buick Regal. That's one of my legacy cars that I'd like to have back!
If I recall, that compressor had variable capacity based on heat load. There was a swash plate unloader mechanism modulated by refrigerant pressure. This ensured greater comfort when running air conditioning. The only purpose of the clutch was to engage the compressor when selecting air conditioning. The later short compressors used the magnetic clutch to cycle the compressor as controlled by the pressure switch resulting in a less refined load match.
Not the A6, it had fixed swash plate. The use of a POA valve in suction line that would take the overflow of higher speed and still get oil back to compressor when exp valve flow was reduced for a cooled interior/low fan speed and refrigerant flow was least.
@@jimmyaber5920 Great info! What happens when a POA valve eliminator and corresponding expansion valve is used when converting to R134a. Is it doing the same job as the original POA valve but just set for r134a evaporator pressure?
Fixed swash plate. Regulation was accomplished by a valve that bypassed the dashboard heat exchanger when things got too cold.
The CCOT system. Had a 4 cylinder Phoenix in the 80's with that system which worked well and was much simpler but the cycling of the AC clutch was annoying -the engine would buck and surge when the AC was set to low cool.
GM air conditioning was the best by far, I grew up in a state where often it would get over 100° in the summertime and those 70s cars with real metal Chrome could get very hot to the touch, and I remember in just a few minutes and frigid cold air would come out of those vents and it was amazing!
Typical GM to take something they had perfected and made world-class and then ruin it, there were SO many other ways to save weight or increase efficiency in their cars rather than getting rid of one of the things that really was the standard of the world.
Also,
I remember being in a less popular (possibly off brand car) that actually would sometimes blow snowflakes out of the vents, maybe it was faulty in some way but it sure was refreshing on those very hot and humid 90 degree nights! lol
You're spot on about them ruining it. Our 1986 Electra had the most worthless a/c and heat I've ever seen. Incredible 180 degree turn for the worse.
@@psymi-hk1fp we "upgraded" to an 85 LeSabre... with a V6... from that 72 Caprice 400ci...
Although the Buick had tufted velour power seats etc, what a step DOWN.
The ac was of course, far inferior.
And it has to be driven in "low drive" most of the time because "regular drive" clanked in and out of overdrive so much it sounded, and felt, damaging.
It LOOKED good for the time, much like your Electra, like contemporary more expensive Olds/Caddys, but what a hunk of coal otherwise.
My folks, who had owned large GM domestics from the 1950s forward, always missed that 72 Caprice.
(61 Impala a close second.)
The 1992 Caprice 305 is nice (and still runs at over 200k), but just can't match that ride and effortless power of the 72 Caprice.
And the "new" 92 ac NEVER cooled as well, even when new, on full blast, nonstop.
Sigh...
The GM cars we owned back in the day did not have this feature. The '70 Buick Estate Wagon had a separate setting for recirc called "max" for A/C. The '80 Oldsmobile had A/C settings of "max" "norm" and something called "bi-level". On both cars you could actually run the A/C on max and adjust the blend door to your preferred temperature. This had the benefit of keeping dirty outside air out of the car. During the old smog days this was helpful. But you could only use this selection for A/C. I remember this feature and as a driver today on my new Toyota I choose to recirc air because of the pollution. On the new car it's a button that can be used on all settings except for defrost. On occasion my new car thinks its smarter than me and reverts to fresh. I smell the exhaust and then have to re-engage the button. I like the new car but still prefer the setup on the '70 Buick. It's easier and does what it's told. Fun story - In the summer back in the day as a 16 year old I would get the Buick to the State highway intersection, turn east and punch it. With the A/C on. The car would hammer to 60 leaving a huge brown cloud of unburnt hydrocarbons on the highway, my 120lb frame smashed to the back of the drivers seat as if I was a 250lb man. I remember my cousin riding along looked at me and said "455 don't care."
Both my Honda and my Hyundai fight with me if I try to use the defogger in recirculation mode, but they give in if I keep hitting the button. The setting is useful when trying to get the ice off the windshield fast, but it does risk fogging up the windows while underway.
Very nice, our old Buick Electra had a control like you showed with the Recirc marked and yes it was Arctic cold even in summer 😅. I also loved the old AMCs with the “Desert Only” Weather Eye setting, it kept the compressor on all the time but I don’t know if it also triggered recirculate or a higher fan speed.
R12. Good stuff. In the 90's the government made it impossible for a DYI'r to buy R12. So, I took an online class and got a certificate that allowed me to buy R12. I bought a 20 lb canister of it. I still have it. I would use it every 4 or 5 years to top off my 1977 Regal, 1975 Park Avenue and 1978 Eldorado. The AC in these cars was terrific but I never liked the automatic AC because in Florida you just can't get it cold enough. The recirculation feature was I beleive not available on that system. The Regal had manual AC with recirculate and it was great but the cabin was smaller too. Good video.
So glad by the 90s, most vehicles had a separate A/C button to kick on the compressor and a seperste recirc button. Can't believe it took everyone that long to figure it out.
How did you ever find such a low mile masterpiece like this? Absolutely stunning!
I think the reason the system would only blow on high in the recirculation/Max position was to prevent the evaporator from icing up . This was particularly a problem in the expansion valve type systems in humid conditions as is common in Florida. It was common for Fords and Chryslers to ice up on long trips because the system would be left on recirculate. Even if the fan was switched on med or low it's less likely to happen with those that have the orifice tube systems or any system that cycles the compressor. I think the elimination of that feature coincided with the introduction of the cycling compressor.. Although the expansion valve was supposed to prevent icing, it wouldn't do it so well at low blower speeds in recirculation position. It wouldn't be as apt to freeze when warmer outside air was blowing across the evaporator .
I wonder. A late uncle of mine who was one of the few "car guys" in the family owned a '76 or so Grand Prix which had the later AC control layout with MAX/Normal/Bi-Level AC settings and no forced high-speed blower setting on full cold, and if that car's AC was run on MAX for enough time with the blower at a lower setting the evaporator would freeze up until no air would flow through the vents, and the ice on the low-side line under the hood was as thick as a baseball bat with ice! :D So then he'd just set it to vent and let it defrost before switching back to AC. Memories sitting in the middle of the front seat of that car in the mid-late 70's between my uncle and dad on a family vacation trip where by being stuck in the middle seat I had control of the AC and the AM/FM stereo radio which was not so common an option back then! Dearly miss my uncle and also miss that Grand Prix, he let my dad drive it and dad said it was the best car he'd ever driven at the time.
@@terrybeavan4264 I think many of us have similar childhood memories of sitting in the middle seat. Today’s kids will never know because no cars have a space for a middle passenger in the front seat anymore. Unfortunately, although it’s a lot less common due to various temperature sensors , the icing issue hasn’t been completely solved even today, especially on longer trips in humid regions.
Im a mechanic and specialize in ac repairs. Been doing it for roughly 13 years. Chevrolet has the coldest ac ever. Especially the 80s when they were leaving r12. They hit it on the head and government made them seitch to 134a
Charles Kettering of AC Delco GM invented freon AC and electric start auto electric for cars trucks.
Also He invented first Diesel electric Train Zephyr and Detroit diesel two stroke diesel.
Look up "Kettering Sperry Bug " first aircraft drone made after ww1 .
Great memories of the 74 Cutlass Supreme we had from brand new. I enjoyed seeing your car. Clearly one of the best AC systems ever.
My father had almost the same car, 1973 red with white vinyl roof, Cutlass Salon. One of my favorite cars.
I absolutely remember that odd setting of the temp lever to the extreme left to obtain the recirculating or Max setting of the A/C on my parent’s 1974 Chevrolet Monte Carlo. It was a great looking car but turned out to be a lemon. Too many issues to describe here. After 3 years, they traded it in for a new 1977 Buick Regal Landau. That car was a beauty and had excellent quality control. Thanks for all of your videos on all the various makes and models of cars. I look forward to them everyday!
As I recall, the recirculation "fan" always ran even in the off mode. The other thing about the Oldsmobile rocket engines is that when the heat was on especially in vent mode, they had a very distinct aroma. Now that I'm thinking about it, my 1979 Park Avenue Coupe had the Olds 403 6.6-liter engine. It also had the Oldsmobile distinct odor!
The owners manual for my 75 Firebird states the fan is designed to run even in the off position to keep air moving through the damp AC unit to prevent mold and mildew......it also created a nice chilly draft under the dash in the winter however it could be switched to an annoying hot wind on your knees.......anything but completely off even if the car was comfortable without using the heat/ac.
@@jasonrackawack9369 I still have all of the owner's manuals from all of my cars from that era to the present era. I recall the same type of info.
I think that started in the 1970's on a lot of makes.
My 01 Malibu and my buddies 98 Silverado both would let air flow through at highway speeds. The fan was off but you could definitely feel warm or cool air flowing through depending on where the temperature was set
@@imthemistermaster I have always heard this was a deliberate safety thing, as it means there is always fresh air entry to the car when in motion. Probably more that they didnt see a need to install a damper to totally close off the system when its off since very few people shut the HVAC on a car totally off. I usually ran vent mode if I did not need a specific thing for example.
The weirdest quirk I know of in GM HVAC is that you can't turn the fan to actual "OFF". I've _never_ had a GM that would actually shut the blower down. It's really fun when the bearings start to fail in the blowers and you get the tell tale rraaarrarwwwrrrrrrrr which cannot be stopped. 😂
The fan however had a thermal switch in the circuit to kill the fan when the-in car temperature was below 40 degrees and the slider was in the off position. This eliminated cold air discomfort in the winter during cold startups.
@@Earcandy73 I'm not sure about that one across all models/years. I have one in my driveway that is about 2 degrees off of being tested. 😁
yes, when I had my 1971 Fleetwood in FL, and the AC broke, that fan kept running even in off, pumping in hot air! Not great for FL.
many later cars had that "always on low" fan feature, but if the system was turned off, the fan was actually off. (depending on the make) MOPAR had the low fan deal that was on any time the HVAC was on, although you could defeat it by slightly pulling out on the heat button. (button system, not sliders) I was aware of this issue on late 60s full size vehicles because people complained of the excess draft or overheating in the passenger area. I guess they were too lazy to move the temp lever.
Someone once told it was because of Nader and was to keep fresh air coming in
In my opinion the compressor you show here and Chryslers V twin compressors were the best that were ever used in automotive air conditioning. I’m retired from HVACR field after forty seven years I never did any automotive air conditioning except for my own and family. I really liked those two compressors they seemed to run forever and would take more abuse than today’s compressors. It’s the same way in the field I was in.
the Chrysler V Twin could be converted into a normal air compressor for air tanks etc.
I never tried it but I’ve seen it done. It’s a shame when America has something so good on the market that they have to stop manufacturing it because it doesn’t break down and make them money. 😡🤬
@@czechmate6916 Yeah, that seems to be the first priority in modern automotive design.
Just one more reason I'll keep fixing my old cars! :3
@@jamesgizasson Same here, everything I own is old but it’s paid for and still works while everyone else is in debt for buying junk they don’t even own anymore. They have to buy new junk 🤣
@@czechmate6916Yeah. I used to hate modern cars because they were so expensive and complicated. Now I hate them because I know that all that money doesn't actually buy you a better car... just a prettier one.
A couple of years ago I was melting while picking up a friend's kid from school. Long line, pull up 2' at a time, blazing hot parking lot, no shade--like a traffic jam. I had a new Honda Fit, huge windshield, sunroof w/shade closed and AC on full blast. Nothing. I was like--Really?? Are the summers this much hotter? No, it's just not an old GM unit.
'60s/early '70s MoPar and mid-'70s-up GMs have just AWESOME air conditioning. I don't think anyone's ever done it better. If it's not hot and in the daytime, the old GMs I had and my '67 Belvedere's temperature setting would rarely be more than like 1/8" toward the 'cool' end of center, and I almost never turned the fan above the first or second setting, usually in defog/floor. Max AC/recirc was strictly an 85°+ with the sun out situation.
they sure had a spectacular fall from grace.... my family had a 1986 Electra Estate Wagon, and it had the most feeble A/C and heat I've ever seen.
@@psymi-hk1fp My '80s Buick Regals remain the most impressive vehicles I've ever been in to this day with regard to AC frigidity. There was something wrong with yours, I can say that with 100% confidence.
I had a 1975 Caprice Classic that utilized that setup and man, that A/C kicked! Never had a hot day that thing couldn't beat!
I actually met the guy that designed the AC for my Olds Achieva (97) at a gas stop in Georgia in August, he asked how I liked it? I told him I knew when the turkey was done in minutes! That was the best AC I’ve ever had in any car I’ve ever owned!!
My Pontiac wagon (73) was amazing too!
When I went to GM Training Center in 1973, they taught us to rebuild the A6 compressor with Vaseline because it had low melting point and would mix with the compressor oil.
I have a ‘63 Sedan deVille w/AC. That car is now 60 yrs. old. I’ve owned it since 1980. It still blows ice cold and always has. I have never had to add refrigerant. It does NOT have a recirc feature at all as far as I know.
I’ve also had a ‘73 Fleetwood Brougham d’Elegance (60 Special) and a ‘75 Buick Electra Limited Park Ave. These cars both had the recirc position as you’re showing on your olds. I’m presuming that they had the Compressor that is the subject of this video. While they both did speed up the fan and switch the position of the mixer door. But they also leaked out. I had to add refrigerant just about every season.
As to other makes - I’ve had 9 Chrysler Mini-Vans. 8 of which had AC. They all had a recirc button which sped up the fan. However several of them quit working at the higher speed after some time!!
GM is well known for their A/C, at least they used to be. I grew up in the back seat of my Mom’s ‘84 Park Avenue and she kept a blanket in the back seat for long road trips. I think only Toyota tops them for A/C. My cousin had a late ‘80’s Camry and that thing could blow ice cubes even with its 4 cylinder engine.
Thanks for the memories! My second car was a 1975 Olds Cutlass Supreme, so your controls description was very familiar to me (from 1981-1982)
The only way I can get Recirc / Max AC in my 1994 Cadillac is to set the temperature on the digital display to 60 degrees.
When set to 60 degrees the air is recirculated and the blower automatically goes to maximum speed.
What sucks about this car is that there is no way to select bi level air conditioning.
My first car a 1975 Ltd had this fridgedaire system on it with an expansion valve which kept the compressor on constantly so you didn’t feel kick off and on all the time and it all these years later was hands down the best ac system Ive had and im a ford guy. I’ve been mechanicing almost 40 years. Time flies
My 1974 Lemans coupe had the same functionality 😊
I remember this feature very well, it caused a return to the dealer early on when the parents first got the 73 Caprice coupe. Needless to say, they had the temp lever all the way to the left so the fan was on high when in AC mode. Our 69 Caprice had a separate position on the control lever for the recirc AC mode. No problems once the operation/control was explained to them. I have to comment that this control was super easy to use, everything could be controlled by "feel", provided you remembered the relative detent positioning on the top control mode lever. Funny that you mention the heater core hose control valve, I don't think the 73 Caprice had one of these.... The only reason I remember/noticed is because I changed the heater core/heater hoses so many years ago and would have remembered a valve like that.
Peculiar features do get replicated though. Believe it or not, my 09 Camry has a similar control feature. Turn the temp knob all the way to cold engages the AC recirc mode and a higher fan speed! This feature is ever more frustrating on my Camry because it acts like a switch to turn the AC on even though the AC switch might be off. The temp control knob must be turned away from this position before the AC will shut off. Needless to say, this foolish design flaw has resulted in some colorful commentary by yours truly.
For my money, the HVAC control on the old Chevy (no comfortron) was great. You could make any adjustments to the system without having to look at the controls, or some idiotic screen.
For sure. You can't beat the old GM systems for simplicity, cold AC, and hot heat....
What you say is true, and 100% your experience. I like these controls, simply because it was ubiquitous. Everyone had a GM, and if you drove another's car you could figure it out instantly. That doesn't make it the best. Honda climate controls had all the same features with 3 dials, and they kept the same design in every model. expensive or cheap. Again, the same easy to operate and the dials, for me are easier to work with no look.
@@Redmenace96 Yeah, my 99 Solara had the three dials as well, with good detents, easy to use as well
@@fleetwin1 O, was I mad when Toyota and Honda went to touchscreens. Like every other car company. Wanted them to fight the power and keep it as simple as possible. Nice to hear a nice comment from a nice YT viewer.
Sounds like that blower motor needs a rebuild!
I was sure you were going to discuss the flow-through ventilation on the early ‘70s GM cars, with the louvres in the trunk lid to enhance ventilation.
Ah yes! The 1971 only louvers!
This content is completely irrelevant but for some reason it is fascinating to me. Keep up the good work. I love your videos.
My dad had a '69 Buick Wildcat with that deep-freeze compressor. It could be over 100 degrees outside, and the inside of the car would be like a meat locker.
The '70s. Where GM took an Air Conditioning system and built a car around it. 😂
Seriously, in February of 1988, I bought a 1976 Oldsmobile Cutlass. The A/C still worked perfectly. 12-year-old A/C that could damn near freeze you out of the car on a hot summer's day. Glorious stuff!!
GM really had the best air-conditioning. I really back in 79, my Boss drove a Mercedes and he went somewhere with friends and they had a Cadillac and he commented how nice the Air was,
I feel like early late 80s- early 2000s Fords had a similar setting but it’s with a dial.
Panel setting turns off A/C, upper vents, blows outside air
A/C turns on A/C, upper vents, blows outside air
MAX A/C recirculates air, upper vents, and high fan speed(maybe others) has more blower motor power than any of the other settings on the dial.
Make that "many of *its* 1960s/'70s era cars" -- no apostrophe.
I know. Autocorrect loves to do that-and I sometimes don’t catch it. Annoying.
I had a 1979 Ford Thunderbird with an Eaton compressor and I had a 1979 Ford LTD with the A-6 Frigidaire compressor. Both cars had good air conditioning and I never had an issue with the Eaton compressor. That A-6 IIRC had the compressor clutch mounted in rubber on some of the later models and it came apart on the way home one night. My dad had an A-6 from a 1967 Buick Electra under the work bench and we pulled the compressor clutch off that and it fit perfect. I drove that car 200,000 miles and it was still blowing cold. GREAT VIDEO!
Come to think of it, in my 2016 Camry, if you turn the temperature knob all the way into the blue zone it puts the system into recirculating mode, despite the fact that the HVAC panel has a dedicated Recirc button.
But turning the knob all the way into the blue zone has no effect on blower speed.
Love this! I don't remember you featuring this car on UA-cam, but those Cutlass cars were a sweet design that circumvented the Nader bumpers so well. Thanks for sharing!
Yes I remember this, my 1975 Cutlass had the same interior as your 1973. Thanks for the review.
I'd recognize that 1975 Olds Cutlass dashboard every time!
Few years back we sold dad's original 1975, 12k mile red w/white stripe, 455/th400 car he ordered new from charnock olds here in Dearborn.
It went to a good new home.
😆 As a kid in the 70s and driving teen in the 80's with a family that was up until that point almost exclusively GM, I always thought the GM air conditioning controls were the most ridiculous and non-intuitive systems ever created. Now I know why...(sorta!)
I was so appreciative when I finally bought an old used Mazda and the climate control system actually made sense (ie, controls for 1-fan speed, 2-temperature, 3-AC compressor on/off, 4-recirc, 5-vents used). Thanks for the memories! 👍
I love those GM A6 axial compressors. They were big and heavy, and it took a lot of power to run them. But they worked. And they lasted. The Harrison compressor that followed was complete junk. They were often called pancake compressors due to there design, and you could count on them failing every 2-3 years. They almost always started leaking where the end caps were welded to the body. They were very flimsy. They used a lot less power to run, and that may have been the reason why GM switched to them. I have a 1976 Corvette with the A6 compressor, and it will freeze you out. That control design is similar to more modern designs that use "MAX A/C" to get more air, and use recirculated air rather than warmer outside air.
I have a 2006 Mercury Grand Marquis, and it has a real nightmare of a climate control system. It uses constant flow of hot coolant through the heater core, and has a "blend door" to mix hot air and cold air to give you the temperature you want. The big issue with this system is the "blend door actuator" a small cheap plastic box with a tiny 12V motor and cheap flimsy plastic gears in it. These things inevitably fail after a short time, and their location makes it necessary to remove most of the dash to replace them. Mine failed. After doing some research, I found that I could remove the passenger side airbag, fabricate a chisel out of a 20" piece of rebar, and get it back in there far enough to break off the corners of the blend door actuator where the attachment screws went, and move it away from the bellcrank on the blend door. I was able to jam the blend door into the full A/C position. I also removed and plugged the heater hoses to keep coolant out of the heater core. I live in Phoenix, AZ, where summer temperatures average 110-112 degrees F, and it never gets cold enough in the "winter" where a jacket won't keep you warm. This nightmare could have been avoided if only they had used wire cables to move the blend door. They tend to last forever.
I had a few Panther cars and that blend door actuator motor is a common failure point. The good news is that it's possible to replace it by just pulling the glove box and the passenger side airbag. You only need to destroy one corner bolt as I recall. It's not *easy*, but it beats trying to pull the whole damned dashboard out.
Very similar to the way 1985-1993 DeVille only used recirculation when temp was set to 60
I always found the 80s to early 90s slider HVAC controls in GM products quite confusing as a kid on what was supposed to perform what function. The unit Chrysler used in the early 90s k based vehicles took no time at all to figure out with its visual directional diagrams assigned to a single button, button specifically for air conditioning, and a slot for recirculating.
When I saw the video title I knew what you were talking about. Its true what other commentators have said these were the coldest A/C systems ever put in cars. Had one in a 73 GTO in New Orleans and it would freeze you out after a few minutes in that mode.
I have that in my 1973 Buick Limited as well. I always wondered exactly why they did this, but it works well so no harm, no foul!
It did not go away. That is 5:43 simply max AC on almost every vehicle on the road today with AC. I can’t believe you find it amazing when it’s a standard feature everywhere.
I had several Olds mobiles during that era, including a 73 Cutlass. The A/Ć control with the MAX detent was for hot humid climates like deep south and mid west. As it was explained in my Owners manual, initial startup in hot car meant rolling down the windows, start engine, put cooling on the system on "MAX COOL" setting, anf be careful about touching hot interior surfaces. As driving time accumulated we began rolling windows up until the two front ones were open 2 inches. This allowed maximum cooling effect and helped to quick flush the hot air out. The, once the windows were shut, reduce cooling switch to Normal setting and enjoy the ride.
The a/c in my '72 Cadillac Coupe DeVille was the best system in any car I have had and potentially will have.
I remember that my 77 Pontiac LeMans would set the fan to Hi whenever I switched the control to “Max A/C” this was a new experience for me. It was a good A/C system especially with that R-12 which at that time was $2 a can at K-Mart.
I agree with your description of the fan speed increase on recirc (since you can clearly hear the fan noise pitch increase) but am reminded of a car-nerd debate I got in with a Honda owner, who thought the same was happening on their 1990 Prelude. Another independent noise effect also occurs when a car's HVAC is switched to recirc - the passenger cabin becomes exposed to the inlet-radiated noise of the ventilation fan, which can make the fan a lot noisier (even though it is not passing any more air, nor has its pitch changed).
That fan speed feature is very cool. I don't recall ever seeing that on any other make of car.
I knew instantly what you were going to talk about when you mentioned "GM only". I believe I first saw that on the 71 GM cars. And, it was a feature that I hated! There are a number of times where you might want the A/C in the recirc mode, without the hi blower speed. Had I owned a car like that, I would have immediately rewired it. On the other hand, that A6 compressor was considered to be the best compressor ever, because it was smooth, quiet, and lasted forever. However, it weighed a ton, and needed a fair amount of horsepower to run it. What is funny is that GM went from having the best A/C in the world, to having the worst, once GM went to the horrible R4 Harrison compressor.
I switched the vacuum lines in my '86 Dodge Lancer so that it would always be in recirculation mode. Before that, it only recirculated when the slider was at the coldest setting, so if you wanted it cool but not freezing, you got clammy outside air.
1. That a a real clean looking under hood. Looks beautiful.
2. I had a 1962 Olds Dynamic 88 and the A/C vents on the dash were metal balls chrome plated. It would get so cold that frost would form on the vents.
I recall talking about these systems while at GM school in the mid 70s and I believe they were almost 2 tons of AC with a bottom line of about 38-42 degrees air temp at the center vent, which was quite a bit lower than other makes of the era. Heck, these days my 2014 Dodge is hard pressed to go much below 50 degrees unless it's an overcast / rainy day. BTW, not sure when GM went to using barrier style AC hoses but was told by many the R-134a conversions can leak right through the rubber on the older style. Have done a few conversions on 80s vintage with few problems there. The GM systems had enough extra capacity to deal with the slightly less efficient 134a. Not so an all other systems. I also still have a couple of one pound cans of R-12 in case I stumble on an older system that needs a top up. Makes me wonder what else is in the back of my garage, eh?
Surprised you didn't mention 'Bi-Level' ... heat on the floor and cool on the top vents for those cool sunny days.
I own a 1975 Cadillac Eldorado, and the system is quite similar to this one, A6 compressor, VIR diverter valve, and also is equipped with automatic temperature selector wheel in the control panel and with a "computer controlled" 😀module under the dash to select the vents, temperature and fan speed. All working flawlessly like the first day.
Back in the 90’s, my boss said a lot of good things about GM air conditioning systems.
I watched a mechanic rebuild a compressor once and I believe it was a GM automobile that he was working on.
My former 1971 Riviera had that. And if I recall, so did my 1976 Sedan DeVille.
I drove an International cabover 943,000 miles, owned by Ryder truck rental, every 200,000 miles the R-6 compressor would give out, I’d be close to a “Ryder Service Center” , pull in and get a “re-manufactured” R6 compressor @ receiver dryer changed out. We ran Ca = west & Fla = east year round. The re-man compressors lasted as long as the new unit did. Very dependable in hot summers in the southern states
Mid-1980s Audi sedans also used GM AC components.
My dad had an Audi 5000 that blew frost.
Rolls-Royce & Bentley also did, later so did FoMoCo for Lincoln, full-size Mercurys and full-size Fords.
Yep - in the Texas summer, those GM air conditioner units worked great! The controls provided practical function, but I absolutely hated not having independent manual control. Good thing those barges took all the joy out of driving and it was just an appliance - that was well suited to the Texas driving conditions.
Very cool! I didn't know they did that. I was guessing this was gonna be about the crotch cooler vents so i was pleasantly surprised!
In 1973 I had a Mercury Montego company car (very plain...Inspector Erskine from the old "FBI" series rode around in versions like mine). The AC system had the same slider set up wherein sliding it all the way to the left engaged the recirc mode. The doors and baffles were vacuum controlled. I was working in Fresno in sales at the time and was amazed how well the piston compressor pulled the temperature down to very cold while idling in a parking lot while i did my paperwork on the fly. Growing up in a Ford family (and being a car nut) I was very aware of GM's superior rotary compressors and VERY annoyed at Ford's rumbly piston compressors. My parents years later bought a Mercury Monarch that came with the GM 6 compressor. I now understand why we could never use the fresh air setting of the AC: The heater door obviously was not closing all the way in the coldest setting before the detent, so hot air was bleeding into the air flow. The only way we could have that GM cold blast was on full recirc with the temp lever all the way to the left. Also, the GM compressor flung oil all over the engine compartment. At the time I was convinced GM was selling Ford defective compressors on purpose. I never understood why in the early 70's they unnecessarily complicated the climate controls...the Max/Norm/Vent options were perfect for setting the climate just the way you wanted...quickly. Thanks for covering this aspect of GM's designs
My uncle, a Chevy dealer at that time, sold his demo car to my family. The climate control had a temp setting and a sensor on the dash. Set and forget. WAY ahead of its time.
I'm an old school tech. I remember those systems. Don't forget about the vacuum actuators. Those were a pain.
My '75 Monte Carlo had the same setup. Farthest left was MAX air, and then one step in allowed the fan controls to be set. I think by '76 they went to the MAX, NORM, BI-LEVEL setting on the top slider.
Very good reminiscing on old gm ac systems. I clicked on this vid, thinking it was about their insanely frustrating electronic climate control systems. I believe it was called comfortron in their hi end vehicles.
I had 2 cars with this compressor. The 1979 Chevrolet Impala and 1981 Chevrolet Caprice.
with the older R-12 system, I was taught to perform a pressure test to see if it would hold, after a few days if the pressure held you'd then vacuum it down as far as it would go and let all the moisture boil off. Finally, after all that you could then charge it.
We had a 77 Caprice when I was a kid. It had 'max' and 'normal', but anytime Max was selected the fan speed automatically went to high.
I also remember the weird Ford/Lincoln setup back then. They had a Hi-Lo setting that would alternate airflow from the upper vents to the lower vents. Back and forth. I doubt very many people ever used it.
My 69 Grand Prix also had a air- duct that distributed the A/C right to the driver between the seat and center console. It could freeze you out.
Our family's 1976 Oldsmobile Custom Cruiser had the A6 compressor with the "tempmatic" AC, you'd set the temperature and the system took care of the rest, including fan speed. It was awesome. If set manually, it had that detent to increase fan speed as well.
Back in ‘70’s I detailed cars during summer. One regular had a Rolls Royce with a GM A/C system. One hot day he asked me to look at his car to see why the A/C wasn’t delivering cool air. I figured out the condensation on the backside of his metal dash vents had frozen shut. Rolled them over, let it thaw, AOK.
My family's 1976 Cadillac Eldorado Biarritz had the "climate control" on the left hand side of the steering wheel. The thing had a wheel to adjust temp and a bi level basically meaning "in your face and down to the floor" cold air. When you saw an ad for a 70s Chevy advertising "air blows ice cold" they mean it! Chevy really knew how to make an industrial grade ac for an automobile.
It's cold, better than most HVAC home units at the time, and used that toxic Freon 12 (pre 134A conversion) but it sure could cool a car. And Cadillac made sure you were comfortable in the often named "Queen Mary or Titanic". Looked like a land yacht, ran like a land yacht with air ride suspension, and kept you warm and cool in sumptuous leather and HUGE power seats. Chevy and it's GM associate brand (Pontiac, Oldsmobile, Buick) really make their cars unique and each is special in its own way. I miss the days of charm and character in cars.
Modern GM vehicles (without auto climate control) work similarly. On my 2018 Cruze for instance... When the AC is on and you turn the hot/cold dial into that final notch all the way cold, it engages recirculation (if you haven't already selected recirc with the separate recirculate button). I don't think the fan speed actually increases, but it sounds like it does since recirculate mode always makes the fan sound slightly louder.
My VW does the same thing. It's marked AC MAX on the dial and when I turn it there, recirc turns on
I can remember my dad taking an old air compressor from an air conditioning unit and I believe it was GM and I believe it was frigidaire. It was an upright almost looks like a small go-kart engine. He built a small frame and hooked up a washing machine or dryer motor. He braided on the output side an air hose. And said here you go this is what you use to every bicycle tires. You know I use that and still have it.
The Comfortron system was even cooler. It was thermostatically controlled and would automatically switch from heat to cooling as you drove as weather conditions varied.
Having owned many 1971-1976 GM cars, I believe the introduction of this feature coincided with the Forced Ventilation system with the fan that continued to run on low when the system was turned off. Both features were designed to positively pressurize the passenger compartment to prevent carbon monoxide buildup in the event of an exhaust leak. Recirculation mode still had a small percentage of outside inducted, but this was enough in terms of volume as the fan speed would be on mandatory high.
That doesn't seem right because on max air it would recirculate the inside air. Recirculate did not add any outside air. I worked on vehicle ac in the 1970s
I read this someplace credible at the time, quite likely at least one of the owner's or shop manuals from the multiple 1971-76 GM cars I have owned. It makes sense given the engineering emphasis of the systems, but I have no way to know how to confirm it, or if the divisions were given a choice in the matter (I would suspect not).