Residential Low Voltage HVAC Troubleshooting Class P2
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- Опубліковано 5 сер 2024
- In this class, Bryan teaches the Kalos techs how to diagnose the low-voltage electrical components of a heat pump and a straight-cool system. This video is the second part of our series on Residential Low Voltage HVAC Troubleshooting.
Techs often make mistakes when stripping wires. When you strip a wire by wringing it with your stripper’s jaws, you can nick the wiring. Generally, you’ll want to make a small split in the casing and gently use your wire stripper to pull back on a conductor you won’t use. That way, the casing will strip away quite easily, and you won’t risk nicking any of the important wires.
When routing wires into a heat pump, make sure that you keep those wires away from the air handler. The indoor coil can become quite hot in heat mode and damage the wires. You will also want to avoid vibrations and sharp edges that could damage the wire.
You can ohm out your wires to look for open areas in a circuit that’s not energizing. Before you attach any wires to the HVAC system, you can check for breaks in the path with an ohmmeter. You do that by connecting all of your conductors together and putting your meter leads on two different conductors at the same time. If you have an “open” reading (infinite ohms), you have an incomplete path. You DON’T do this test if you have a blowing fuse.
Wires that are exposed to the sun or excess heat can lose their colors. You can figure out those colors if you connect them to ground while each color is connected to the system.
When we begin diagnosing Bryan’s heat pump system, Aaron first checks to see if the blower is running (it is). He then checks if the compressor fan runs (it does). Aaron also ensures that the thermostat is on and the refrigerant is flowing through. However, the system is supposed to be in heat mode but is cooling. The reversing valve was being energized when it wasn’t supposed to be. Instead of checking behind the thermostat’s face with a meter, the team pulled the battery out to make sure there’s no 24v power. The system appears to have a popped fuse. After the team takes their readings, they use the Short Pro to confirm if the fuse blew. Sure enough, a 3-amp fuse blew due to a short.
Bryan’s team looks for the short using Eric’s method: using an ohmmeter on a de-energized circuit. They look for an ohm reading near 0 on the wire nuts, and they determine that the short is in the G conductor. When the team energizes the system without the G conductor, the system does NOT run as normal due to the thermostat’s overload protector. Then, the team disconnects the wires from each other and decides to connect each one to the 24v power supply individually. After turning the system on to test it, the team discovers that the orange wire (reversing valve solenoid) is not energized. Since the orange wire is connected to the contactor coil, the team decides to check for an open circuit. There is an open circuit between the thermostat wire leading from the air handler to the condenser. The team checks the ohms from the orange wire to another working wire (yellow) for confirmation.
When we begin diagnosing Bert’s straight-cool system, the thermostat is blank. The team quickly notices that there is an open switch that has turned the power off. However, the thermostat remains blank after closing the switch. The team decides to check the transformer where it connects to the circuit board. They set their multimeter to pick up voltage between hot and common. The team discovers that no voltage is coming out of the transformer, and they trace the problem further to the power supply (L1). No power has been going to the board OR the transformer. The team checks for loose connections; there are no loose connections, but some of the switches are off.
Bert’s team checks the incoming power, and the main breaker is off. Once power is restored, the condenser doesn’t come on. It looks like the thermostat’s time delay keeps repeating, so the team works to bypass the thermostat by putting a wire nut on R, G, and Y. The blower doesn’t work, and the team notices an error code. The blackened fuse indicates that a short occurred and blew the fuse. After ohming out the fuse, the team can confirm that the equipment has blown a fuse. The Short Pro indicates that the short occurred on Y.
When Bert’s team checks the yellow wire at the condenser, the meter doesn’t indicate that there’s a path on the yellow wire. There may be an issue with the contactor coil, so the team checks the ohms on the contactor (0.6 ohms). After checking the ohm reading against a brand new contactor (12 ohms), the team determines that the resistance is extremely low; too much current went through the system and led to the fuse blowing and the time delay resetting.
Check out information on the 2022 HVACR Training Symposium at hvacrschool.com/symposium/.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/.
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Very nice video and help full for new learner students, it's not big mistake common person can find out what is the fault into the electricity hvac technician need understand interlock wiring, electronic devices microprocessor plc and DC 12 volts sefty components, ducked ac unit is very common can easily find out the problem
Thus video has nothing to do with inverter systems at all. That would be a different class all by itself. Almost all inverter boards has an onboard diagnostic and whatever fault code you get is on the manufacture label behind the panel. Like Lennox unit. Other units you have to count the slow and fast flashes which therefor gives you a fault number to reference label.
Starting my hvac career soon. I'm so excited that I'm up at 12am watching this!
Man I'm about 5 years into the field now and holy cow these instructors have some patience ! Love the hands on training and how these kids are getting involved! There is still hope for this field!
I’m going on two years but not consistent I admit. I’m looking to gain more experience and knowledge and these videos are helpful
Now just try troubleshooting these furnaces when it’s 150
Degrees in the attic lol
Hvac is something different. Im a jman electrician, been doing it for 7 years and understand schematics and electricity. Just started with an hvac company 3 months ago to help installs and do other normal electrical work. They sent me out on a service call to help a service tech and we both couldnt figure out why the ac wouldnt work. Had a senior tech come out another day to find out it was a shorted coil on the ac contactor. Who would have known, it made sense after he figured it out 😂 but damn. Definitely need to be smart to do this and you really do need to understand fundamentals to be successful.
HVAC SCHOOL is my top channel to go to for learning. Bryan's teaching style and the way he explains things is easy to understand he doesn't try to make it hander then it really is i like that. Every video he posts gives me confidence.
The training is rewarding I love every part of it. The install Crew becomes acquainted and it just brings good vibes.
You’re the best hvac teacher I’ve ever heard! Brilliant and you make it simple
such helpful videos. what a service you guys r giving
I dig the hands on training, I enjoy finding shorts and I do know that a lot of techs don’t quite understand the low voltage circuit, or easy ways to check for open circuits or shorts. Good job!
When I makes some bucks benefiting off of y'all's lessons and wisdom.... I'll give back. Thanks y'all! .
Thanks 🙏
And
Much respect!
👊!
As an apprentice I would kill for this training
I like when students really get involved,this is the best method of learning and the quiz at the end of the class
Ha, his mic has an open @ the end..😉
Awesome instructor you are Bryan. I am forwarding these to my trainee . Keep up your great efforts and you will turn green techs into mean techs.
Never stop learning people. 👍🏼👍🏼.
Great demo for trouble shooting for new folks and a refresher for higher level tech. Thanks for a great show and tell real problem examples.
I sincerely appreciate the genuine aspect of your teaching
I feel comfortable with all of this, but watching this gave me anxiety. I'm terrible in a group setting when learning. With that said, I really wish I had this kind of instruction in school. Great job.
I went to an hands on HVAC school. Taken them apart and put back together over n over again. But also had power point lessons as well. I was always taught to look at what color wire is connect to your R,C,G,W,Y etc. inside the AHU and behind the t-stat because your green wire may not always hooked up to G terminal. Take a picture of the wires behind thermostat so you don’t forget when your at the AHU. But overall great informative information. Now for things for the instructors you must lead by example and if your telling students to wear safety glasses. You as an instructor should also be wearing safety glasses as well.
Being retired Telecom Dept from a Famous Railroad, I might add in the Fall Rats start looking for nesting material, and they go to cables, resulting in shorted or open wires in the Fall!
Mice chew through wires because the insulation is made from peanut oil. I was very surprised when I learned this.
check in from Tampa Florida Thanks
Thank you very much for showing us these videos so bally, God bless you !!
Great lesson, I just had a low voltage problem today. Good stuff wish I was there learning more with yal.
Great class thank you for sharing it!
Man great job. Love the question about common. This is troubleshooting.
Thank you so much...I'm new with HVAC-R and really learning a lot from your videos
Thanks for the content. You are appreciated.
Great teaching methods.
Awesome job. Start at the braindead basics. Knowing this when troubleshooting and you get twisted you come back to basics and start again and verify what is and what is not. Well done instructor. There is real skill in problem solving. Think it through don't be one of the brain dead part swappers. Part swapping only as a last resort to confirm our theory.
Thank you for another great video
Thanks for the video.
Very good instructor
Good teachers whith a los oficiales patience god bless you guys
Good low voltage tutorial i have a lot of getting a new trouble shooting about 24 voltage open wire and how to do this to resolve the problem. Thanks you sir. God bless you sir
Nice job and video
this is my American dream 👍👍👍👍
Man I feel for the guy that got stabbed in the back. I remember getting stabbed by plywood nails in the attic a many of times LOL
those were great tests for your techs.
Enjoyed the video. However, I believe it would be more informative and easier to follow the troubleshooting by the techs to run through each of the scenarios from start to finish before moving on. The presentation made it more difficult to follow what is going on. ( I am a big fan of your videos)
Thank you
Love the lesson
The teachers attitude is aas though
YOU ARE THE BEST
Thank you for having these video. 3 and half weeks from graduation and being certified. This is very helpful for upcoming finals. 😊 ty ty ty. Any tips for the interview I'll go for after I finish school.
great video, please do more combining sequence of operation, thanks
fun suggestion , buy yourself a seem ripper ( for sewing) it works amazingly for pulling the shroud back
Yes Sir! Seam ripper is my go to as well!
Great class!
I would love to work for this company! Del-air did me dirty! Most of the techs are getting OJT and don't know barely any thing!
You can spot the installer with all the mastic on his pants 🤣
Thanks
Great troubleshooting video. Would also add IR megger test for a wire rub out or short the between all conductors to earth. 250-500VDC Plus keep halving the circuit to isolate it. - The Megger is used to measure insulation resistance and other high resistance values, It is also used for ground continuity and short circuit testing of electrical power system. The chief advantage of the megger over an ohmmeter is its capacity to measure resistance with a high potential or breakdown voltage.
A warning to heed when using a hipot insulation integrity tester on low voltage hvac wiring is to isolate the conductors from the circuit to avoid damage to a defrost board, for instance. Also, some coils cannot withstand a hipot test voltage higher than its insulation rating.
I really like the info in this video but I think if you edited it to show one in its entirety and then the other it would be more helpful to us new guys. It gets a little confusing when you talk about doing something and then it switches to another system where they’re doing something else. I needed the info from the unit Brian was working on and it’s harder to digest the info because you guys talk about what to do then switch to the other unit so I had to watch it several times
What I did is go outside and take the cover off the contactor at the condenser. I would check for 24 volts across the contactor if it was not running. If it showed voltage and not pulled in replace the contactor. Then if pulled in and not running check for voltage across the contacts. If no voltage then check the breaker and the fuses. If no 24 v on the contactor then check the thermostat. If thermostat is set to be calling the check red to blue for 24 volts. If no 24 volts check the tx fuse...if good then check the tx and if no 24 volts at rx replace it. This always worked for me.
Nailed it
I personally hate sticking meter leads in marettes for 2 reasons . One its inconsistent and two it gives you a chance to check someone elses ability to properly connect wires and you can ensure you have proper contact with the meter leads
18:00 "cuz you have never made that mistake before" lmaooo
Ooo . Love diagnosing lab faults.. kill power, ohm out contactor coil, then each R, G, BL, YL, WHT to common. Contactor coil should read 12 to 17 ohms ..any lower can draw more current than is supplied resulting in an open fuse.
Tech may find a rub thru cable on ductwork or too many loads on the low volt supply..ie zoning control, 4way reversing valve coil, liquid solenoid, even a faulty tstat circuit itself, or faulty sequencer delay heater if used.
“What human error can cause this to not work?” Lol!
Hi from Germany:)
it's like herding cats 😂
Idk how Brian keeps his cool with this group of students. Half look like they just hit a blunt and don't even know where they are. I would give my left nut to work for a company to invest this much in me and teach me.
I have questions about ,and You may not answer our question but Yorkshire copper fittings with solder ring already built in for plumbing ready for market in UK, but ,we are looking for in USA for AC line .can we use it ? Is there any in the market for HVAC. Line ?
Because It is to use and perfect all the time when copper to copper soldering
Is continuity and ohms the same? I thought the beeping sound was continuity
Ideal stripmaster automatic stripper. $25 TO $30 KLEIN MAKES ONE TOO
If the guy would have started at the main breaker, where he was supposed to start he would've found the problem in 2 minutes instead of 2 hrs...YOU'RE FIRED!🤧 he's now a cap bandit😂😂😂
I do the "ring around the rose" method. BECAUSE... you can do it very lightly, only scoring the outer casing. At that point, you've thinned it enough to just pull and it will rip off. Too many kids with monkey muscles just tearing it open. I've seen minisplits getting grounded out by the romex connector because someone scored the com wire with a razor too hard. You can do it, just be graceful with it
Try using a bic lighter next time. Run it back and forth under sheathing for about three seconds where you want it to break. Then, it pulls right off. Conductors unharmed.
Can someone please explain to me 12:40-14:00 in a different way or what exactly he meant
I been wanting to understand this cause of the problem with the same colored wires
Also, the reason that the one guy mentioned all the low voltage being pulled outside at a super market is because it was a light commercial/commercial unit where the transformer is outside
36:30 - The type of fuse used here has test terminals in the top on either side of the rating label giving you the ability to test its integrity while in the circuit with power on: if you measure nominal voltage (24vac), then the fuse is blown; if 0vac, the fuse is intact.
Instructor tells the students to put on safety glasses, but doesn't put any on himself. 😉
if one winding on a coil or transformer is shorted they will still read resistance but parts are still bad and will not work properly.
Crocs n socks !? I’da Been sent home off rip
I will usually use my razor gently around the other jacket to expose the rope pull it down from there and cut above where I scored with my razor
I have a nest thermostat intermittent issue where its losing power e73 error code every two weeks or so. Ive connected a common and confirmed 24v at baseplate. Ive replaced the thermostat itself and baseplate, checked all low voltage wiring to ground and between each other with no continuity. Ive also replaced the contactor. All wiring connections seem secure. I got a call back and replaced the board now and transformer. If this doesnt solve it what else can it be im at a loss. Only other thing i can think of is somehow its losing power at the outlet but homeowner is saying when it happens other electrical items are working.
Also no float switch on this system
Run new wiring to the thermostat
First, I would switch the hot (red) and the common (c) with two other conductors like the fan and the heat wires. In other words, you probably have white to w and green to g, just switch those. If it continues after that then look to the door switch, or a loose connection. If no loose connection then you might have to replace the wire. Hope this helps.
@@baileysair Thank you i will
give that a shot
Bosses way is the ONLY way ...ALWAYS
I would have left the sheetrock off so that it could air out and dry and told the apartment manager to have it patched back up after it dries.
👍🏿
How to calculate LRA to amper.
Bert !!!!
The camera person must be a fan of Pulp Fiction the way he/she jumps back and forth from one scene to the other.
Bryan stick with your technique from start to finnish your super tech is hijacking the presentation and new guys need one instructors A B C also its always good to remove wire nuts see if they prepared connections properly , his comment about tie points at unusual locations not needed here either good class.
How could I join the school
I really wanna get into reefer units but there’s no school for that.
If you have refrigeration skills, than get a job at a seaport. Thats where reefers are maintained until they are either loaded onto a ship or a truck. Carrier has a one week course, Its in Long Beach, Ca.
Get your foot in door first. A good reefer mechanic is a combination of electrician, electronics tech, and refrigeration tech.
Every one need safety glasses.
🍺🙂👍🏻
digital non programable thermostats are less problematic then the programable hands down,,,i remember having calls because the ther was not programed correctly ,,,,and they are all a little different ,,,you need the paper work for it ,,,,,i just hate them ..just saying ok back to the class ,,,,,,fun fun fun
NUMMOS ALIEN @ 1:06:21. .THEY LIVE,BERT LIFE!!!
If you didn't bleed you didn't work
Way to much going on to understand wish someone would break it down in an order by themselves it would be much easier to understand
Not a big deal 😂😂😂
Teacher yells to much they need hand on