The A/C compress clutch stopped working?

WHTWUZTHAT

MEMBER
2004 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
245,000 MILES

I have the truck listed above Z71. The A/C light on the control indicates A/C is on. I can bypass the relay and the clutch engages, now I don't know where to go from here. All of the associated fuses are good, and I swapped out the relay with the horn relay which is working for the horn still nothing. It seems like my problem is similar to a post by SGPON, but the posts stopped before the solution was solved.

6 Replies

KEN L

MASTER CERTIFIED MECHANIC
47,722 POSTS

No problem, the first thing I would test is the pressure inside the system because if it is low the system will not turn the compressor on.

Here are two guides that can help us fix the problem:

https://www.2carpros.com/articles/air-conditioner-how-to-add-freon

and

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

Please go over these guides and get back to us.

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Monday, May 15th, 2023 AT 12:05 PM

WHTWUZTHAT

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I replaced the climate control module on the dash. Still no go. I have continuity through low pressure switch but had no current at the switch next to the compressor. I can't find a temperature cutoff switch (not sure if that's the correct name for it). Only high and low. Also, I have about 5volts through the low-pressure switch. I looked through the front grill and can see some little sensor in front of evaporator (or condenser). Thought it may have something to do with the airbags so I didn't want to mess with it. Double checked all fuses inside and under hood all test good. Swapped the relay in the fuse box under the hood with my horn relay which I know is good. So, at this point I'm no closer than I was. By the way don't remember if I mentioned it but the ac light on the control does come on when pressed. Any ideas now I'm about to just give up and settle for no A/C.

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Wednesday, May 24th, 2023 AT 4:22 PM

KEN L

MASTER CERTIFIED MECHANIC
47,722 POSTS

I would try the compressor relay. Also, here are the A/C wiring diagrams so you can see how the system works. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Images (Click to make bigger)

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Thursday, May 25th, 2023 AT 5:11 PM

WHTWUZTHAT

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4 POSTS

Thank you for your help.
I have tested my low and high switches and the ambient temperature sensor all tests good. I have swapped out the AC relay with a known working one of the same number. I can make the compressor turn on by jumping across pins 30 and 87.
Today I went to look at a few more things on my truck and it wouldn't start. I would turn the key to crank, but the engine wouldn't turn over. I checked for voltage at pin 30 of the start relay and had 12 volts. Nothing at the other pins when key was turned to crank. I also tested to see if the relay activated by completing the ground circuit saw no changes. I could jump across pins 30 and 87 of the start relay and the engine turned over and started. I load tested the battery and it was good. Now all I can do is step back, scratch my head and say hmm.

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Friday, May 26th, 2023 AT 9:17 AM

WHTWUZTHAT

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4 POSTS

It's working now. Must have been a corroded connection. I unplugged and inspected every connection associated with the A/C and now it's working just fine. I also had a bad connection between the fuse and the wire that connects to the fuse on the ignition circuit. I don't drive this truck and I guess things just start corroded with age, kind of like I do.
Thanks for all your help with this, you guys' Rock!