here are some links to what you can use if you don't have spare vacuum line and tees about: Tees: amzn.to/3hEH8mj Vacuum line: amzn.to/3g7trMC Note: These links may be affiliate links, which earn me a small commission at no additional cost to you!
I have a 1984 turbo diesel Mercedes and my A/C works perfectly even on a hot day in the 90’s. But know some people have had problems with there A/C in those W123. I guess was lucky.
At some point they started using a different type of condenser and stuff, I feel like it was around 85 though, and you're absolutely right, climate also has a lot to do with it, humidity and temperature has a massive effect, 100F but low humidity my AC does better than 90F but high humidity. Where I live is near a lake and in the summer it can stay over 100F for weeks and it is miserable on even modern AC systems.
It is nearly all gone, the camshaft was worn down on one lobe, and had damaged one rocker, after replacing that there was some leftover knocking sound, which replacing the injector nozzles and balancing the pop pressure got rid of basically all of the remnants. Just drove the car 1500 miles on a trip to the beach and back, ran basically flawlessly the whole time, no noise or weird behavior.
No heat and no cold is an interesting failure. I would verify the fuse for the climate control is good, and from there, first thing I'd check for AC is toss a set of gauges on and see if there is pressure. If there is, jump the pressure switch on the receiver/drier, and see if the ac clutch engages and blows cold air then. For no heat it is basically the monovalve is not opening, which is odd because it fails open. Unplug the 2 prong connector on it and see if you have heat. There is an aux water pump but usually you will get some heat without it, and then can go bad and burn up part of the climate control unit, as the aux pump was not fused from the factory for some reason. So those are where I would start, no heat is puzzling, pretty much has to be a stuck monovalve or it is being commanded to be shut by a malfunctioning climate control unit
I don't have a video for this on w126, I've never had a w126 to play with, I would bet it is almost the same exact procedure, I do believe they shared the climate control from w123 to w126 and possibly some of the early w124 as well, but I'm not really certain, just a guess
You still running R12? My car was converted to R134a before I bought it. A while back I stupidly cracked open the temp sensor connection at the dryer trying to figure out why my condenser fan would not come on...... anyway long story short I leaked out some oil and gas from the system. I put a can of r134a back into it and checked all my pressures. Things looked good but I was concerned about the oil I had lost. Anyway I added a can of "Interdynamics A/C Pro R134-a PAG 150 Oil Charge with ICE 32, 3 oz.". Holy mother of all that is......... I can hang meat in my car now. I've got AC vent temps in the mid 30s. I swear by that ICE 32 product.
I have 134a in my cars, and the AC has always worked "ok", but nothing like what you describe, I may just grab a can of the ICE32 and see what it does in a future video, I've got a few other things I plan on doing partly for my own curiosity, but also because it probably needs to get done, like cleaning the evap and drain, as well as checking the temperature sensor, there is a temperature controlled switch as well as the TXV that control the evap temp, its possible if one of the sensors has gotten gunked up and isn't seeing airflow it may be kicking the compressor off too early, I'm gonna do a video soon on cleaning everything out if all goes well!
from my understanding the only 80% circulation rate is for safety reasons. imagine you do a longer trip with AC on, windows closed, maybe 3-4 people inside. without fresh air you will eventually run out of enough oxygen without noticing. at least the air quality will no longer be particularly good very quickly. in most modern cars the recirculation function will be deactivaded after like 10-20 minutes for this reason.
Possible, but I'm not sure, I heard it was something involving the defrost function causing the windshield to fog up on 100% recirc (which I haven't experienced, but I am aware it could be an issue) I know my cars have enough air leaks that it isn't ever a concern of running out of oxygen or poor air quality. My trucks (20 years newer than the cars) have a manual setting to engage recirculation on the climate control knob, which is either on or off, and stays on if you put the knob into that position (which is where it stays all summer long here). I'm sure there is some logical explanation, but I can tell you for a certainty, in the southeastern US heat and humidity this summer, I've not once been uncomfortable in my W123, and my wife has been so pleased with the AC, we're taking it on a several thousand mile road trip in a few months together. That's a win in my book, plus I'm sure the seats will last longer if they aren't drenched in sweat every day.
@@trythistv yes, but when the car was new and all the seals were in good condition, it probably insulated much better from the outside air. i found an article on a motor website and they also mentioned both, the oxygen issue and the defrost thing. my 1988 420 SE W126 has an extra switch, too. according to the manual the recirculation will be deactivaded after a certain amount of time. i personally dont use this function very often because we have usually mild temps here in germany. Btw: i wish you a good road trip. i'm sure the W123 will doing well, these cars are rock solid, especially as diesel
Agreed, I suspect with 40+ year old rubber seals there is plenty of leakage. I've replaced a fair number of door seals and such, but still, I know there is air infiltration from other spots. I've also heard the AC systems were designed (obviously) for the more temperate conditions seen in Germany, and the ridiculous heat and humidity we see here in the southern US is just too much for the system to handle, This modification may not be ideal, but it does make it much more enjoyable to own such a wonderful piece of automotive history, I cannot wait to get the cosmetics fixed, a fresh coat of paint and clearcoat will make the car look much younger from its current state of peeling clear and faded paint. Seeing the color difference in the door jambs and areas untouched by the sun makes me want to see the car prettied up. Planning on that this winter hopefully. I've seen where people have retrofitted a timer and recirc switch from a w126 or w124 into a w123, I may look into something like that in the future, or possibly build my own piggyback circuit to recirculate for a set time period, or gradually open the fresh air vent when the set interior temperature is reached so that it would blend in some fresh air, but vary the percentage depending on exterior temp vs interior temp or something. Thanks much for the thoughts for the road trip, we'll be travelling about 1400 miles round trip, really not much for a w123, I'm brushing up a few maintenance items before we go, I'm expecting a fairly smooth journey, hopefully it ends up going that way!
Hmmmmm I'm not sure. There may be a flap somewhere, I will have to see if there is any info about the manual climate system. I would think it would be possible to modify in some fashion to allow recirculation but I don't know off hand. I'll see what I can find, and I will try to remember to report back!
Thanks for all Mercedes w123 videos. Each one is a pearl that contains useful information to the uninitiated like myself. I too have a standard shift 1982 240D with a manual climate system. I suspect like he automatic systems, I am getting 20% fresh air and am therefore sweating in NYC traffic this summer. Any thoughts regarding the manual system since your Hmmmmm last month. Plan to make your other mod regarding having the fan run whenever the clutch is engaged but I don't suspect it shall make enough of an improvement without more help. Any thoughts even just theories would be greatly appreciated. Thanks a again for all your useful gems.
If you set your climate control to blow nothing but recirculated air, your defrost will not work properly. Most modern cars will not let you turn on the recirc function if defrost is on. But if you live some place where that is not a concern then it is of no concern. I'd convert it to r134a and put ICE 32 in it.
I hadn't thought of that, I know the defrost comes on and seems to work, but I'm unsure what effect the recirculated air will have long term, I haven't needed the defrost a lot as of yet, and its easy enough to undo this change should I find it causes issues. I've thought about adding some kind of toggle switch to allow selection between stock and 100% recirculated air, but I'm still figuring that out lol
@@trythistv Could the recirc defrost issue be addressed by piggybacking the exterior vac line and electrical connect over to the defrost line and connector? Also have you experimented with adjusting the temp setting of the ETR(capillary tube sensor on side of evaporator) to let the compressor run longer? My understanding is that MB set them to protect the evaporator from icing in moderate climates. Most are set to kick the compressor off anywhere from 38'F to 46'F. I've heard of people removing it and setting it closer to, or right at, 32'F in hot humid climates.
@@v.dembsey3355 Possibly, I need to spend some time building my vacuum diagrams for the climate system, that stuff is complicated and just a hair overengineered lol. I have heard of adjusting the ETR, I've been meaning to experiment with that a bit once it gets good and hot, I may just have to pull the kickpanel back off and take a peek soon.
here are some links to what you can use if you don't have spare vacuum line and tees about:
Tees: amzn.to/3hEH8mj
Vacuum line: amzn.to/3g7trMC
Note: These links may be affiliate links, which earn me a small commission at no additional cost to you!
I used a higher rpm blower fan in my w126 , nice mod
You remind me too much of David Wallace
So thats why he seemed so familiar!
Excellent videos. Time effort.
Glad you enjoyed it! Plenty more stuff I'm working on, stick around for all of that!
Awesome tip !
I have a 1984 turbo diesel Mercedes and my A/C works perfectly even on a hot day in the 90’s. But know some people have had problems with there A/C in those W123. I guess was lucky.
At some point they started using a different type of condenser and stuff, I feel like it was around 85 though, and you're absolutely right, climate also has a lot to do with it, humidity and temperature has a massive effect, 100F but low humidity my AC does better than 90F but high humidity. Where I live is near a lake and in the summer it can stay over 100F for weeks and it is miserable on even modern AC systems.
Good video did you ever get your engine knock or tap to completely go away on previous video
It is nearly all gone, the camshaft was worn down on one lobe, and had damaged one rocker, after replacing that there was some leftover knocking sound, which replacing the injector nozzles and balancing the pop pressure got rid of basically all of the remnants. Just drove the car 1500 miles on a trip to the beach and back, ran basically flawlessly the whole time, no noise or weird behavior.
You are very good mechanic can you tell about my 300 d not cool air conditioning and not hot in winter
No heat and no cold is an interesting failure. I would verify the fuse for the climate control is good, and from there, first thing I'd check for AC is toss a set of gauges on and see if there is pressure. If there is, jump the pressure switch on the receiver/drier, and see if the ac clutch engages and blows cold air then. For no heat it is basically the monovalve is not opening, which is odd because it fails open. Unplug the 2 prong connector on it and see if you have heat. There is an aux water pump but usually you will get some heat without it, and then can go bad and burn up part of the climate control unit, as the aux pump was not fused from the factory for some reason.
So those are where I would start, no heat is puzzling, pretty much has to be a stuck monovalve or it is being commanded to be shut by a malfunctioning climate control unit
👍
I know this is a year old video,but do you also have that on the W126 chassis??
I don't have a video for this on w126, I've never had a w126 to play with, I would bet it is almost the same exact procedure, I do believe they shared the climate control from w123 to w126 and possibly some of the early w124 as well, but I'm not really certain, just a guess
You still running R12? My car was converted to R134a before I bought it. A while back I stupidly cracked open the temp sensor connection at the dryer trying to figure out why my condenser fan would not come on...... anyway long story short I leaked out some oil and gas from the system. I put a can of r134a back into it and checked all my pressures. Things looked good but I was concerned about the oil I had lost. Anyway I added a can of "Interdynamics A/C Pro R134-a PAG 150 Oil Charge with ICE 32, 3 oz.". Holy mother of all that is......... I can hang meat in my car now. I've got AC vent temps in the mid 30s. I swear by that ICE 32 product.
I have 134a in my cars, and the AC has always worked "ok", but nothing like what you describe, I may just grab a can of the ICE32 and see what it does in a future video, I've got a few other things I plan on doing partly for my own curiosity, but also because it probably needs to get done, like cleaning the evap and drain, as well as checking the temperature sensor, there is a temperature controlled switch as well as the TXV that control the evap temp, its possible if one of the sensors has gotten gunked up and isn't seeing airflow it may be kicking the compressor off too early, I'm gonna do a video soon on cleaning everything out if all goes well!
@@trythistv Good luck! Curious to hear what you find!
from my understanding the only 80% circulation rate is for safety reasons. imagine you do a longer trip with AC on, windows closed, maybe 3-4 people inside. without fresh air you will eventually run out of enough oxygen without noticing. at least the air quality will no longer be particularly good very quickly. in most modern cars the recirculation function will be deactivaded after like 10-20 minutes for this reason.
Possible, but I'm not sure, I heard it was something involving the defrost function causing the windshield to fog up on 100% recirc (which I haven't experienced, but I am aware it could be an issue)
I know my cars have enough air leaks that it isn't ever a concern of running out of oxygen or poor air quality. My trucks (20 years newer than the cars) have a manual setting to engage recirculation on the climate control knob, which is either on or off, and stays on if you put the knob into that position (which is where it stays all summer long here).
I'm sure there is some logical explanation, but I can tell you for a certainty, in the southeastern US heat and humidity this summer, I've not once been uncomfortable in my W123, and my wife has been so pleased with the AC, we're taking it on a several thousand mile road trip in a few months together. That's a win in my book, plus I'm sure the seats will last longer if they aren't drenched in sweat every day.
@@trythistv yes, but when the car was new and all the seals were in good condition, it probably insulated much better from the outside air. i found an article on a motor website and they also mentioned both, the oxygen issue and the defrost thing.
my 1988 420 SE W126 has an extra switch, too. according to the manual the recirculation will be deactivaded after a certain amount of time. i personally dont use this function very often because we have usually mild temps here in germany.
Btw: i wish you a good road trip. i'm sure the W123 will doing well, these cars are rock solid, especially as diesel
Agreed, I suspect with 40+ year old rubber seals there is plenty of leakage. I've replaced a fair number of door seals and such, but still, I know there is air infiltration from other spots.
I've also heard the AC systems were designed (obviously) for the more temperate conditions seen in Germany, and the ridiculous heat and humidity we see here in the southern US is just too much for the system to handle, This modification may not be ideal, but it does make it much more enjoyable to own such a wonderful piece of automotive history, I cannot wait to get the cosmetics fixed, a fresh coat of paint and clearcoat will make the car look much younger from its current state of peeling clear and faded paint.
Seeing the color difference in the door jambs and areas untouched by the sun makes me want to see the car prettied up. Planning on that this winter hopefully.
I've seen where people have retrofitted a timer and recirc switch from a w126 or w124 into a w123, I may look into something like that in the future, or possibly build my own piggyback circuit to recirculate for a set time period, or gradually open the fresh air vent when the set interior temperature is reached so that it would blend in some fresh air, but vary the percentage depending on exterior temp vs interior temp or something.
Thanks much for the thoughts for the road trip, we'll be travelling about 1400 miles round trip, really not much for a w123, I'm brushing up a few maintenance items before we go, I'm expecting a fairly smooth journey, hopefully it ends up going that way!
Is there any way to do this on an older 123 with the manual AC controls - with no recirculate at all?
Hmmmmm I'm not sure. There may be a flap somewhere, I will have to see if there is any info about the manual climate system. I would think it would be possible to modify in some fashion to allow recirculation but I don't know off hand. I'll see what I can find, and I will try to remember to report back!
@@trythistv thank you, that would be a huge helping cooling this beast!
I would even make it a permanent Solution if necessary
Thanks for all Mercedes w123 videos. Each one is a pearl that contains useful information to the uninitiated like myself. I too have a standard shift 1982 240D with a manual climate system. I suspect like he automatic systems, I am getting 20% fresh air and am therefore sweating in NYC traffic this summer. Any thoughts regarding the manual system since your Hmmmmm last month. Plan to make your other mod regarding having the fan run whenever the clutch is engaged but I don't suspect it shall make enough of an improvement without more help. Any thoughts even just theories would be greatly appreciated. Thanks a again for all your useful gems.
@@mr427m I wonder if it’s 20% recycled and 80% outside air? Or maybe 100% outside air. At least it feels like it here in Florida.
If you set your climate control to blow nothing but recirculated air, your defrost will not work properly. Most modern cars will not let you turn on the recirc function if defrost is on. But if you live some place where that is not a concern then it is of no concern. I'd convert it to r134a and put ICE 32 in it.
I hadn't thought of that, I know the defrost comes on and seems to work, but I'm unsure what effect the recirculated air will have long term, I haven't needed the defrost a lot as of yet, and its easy enough to undo this change should I find it causes issues. I've thought about adding some kind of toggle switch to allow selection between stock and 100% recirculated air, but I'm still figuring that out lol
@@trythistv Could the recirc defrost issue be addressed by piggybacking the exterior vac line and electrical connect over to the defrost line and connector? Also have you experimented with adjusting the temp setting of the ETR(capillary tube sensor on side of evaporator) to let the compressor run longer? My understanding is that MB set them to protect the evaporator from icing in moderate climates. Most are set to kick the compressor off anywhere from 38'F to 46'F. I've heard of people removing it and setting it closer to, or right at, 32'F in hot humid climates.
@@v.dembsey3355 Possibly, I need to spend some time building my vacuum diagrams for the climate system, that stuff is complicated and just a hair overengineered lol.
I have heard of adjusting the ETR, I've been meaning to experiment with that a bit once it gets good and hot, I may just have to pull the kickpanel back off and take a peek soon.