A/C only works when jumping relay?

SIDEWINDER313

MEMBER
2001 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
205,000 MILES

The ax compressor clutch only works when jumping pin 30 and 87. It’s charged with the correct amount of Freon. I have tested about as much as I could but I’m not very electrically smart. From what I understand possibly a bad PCM since it’s not grounding pin 85. The wire between them is good, I checked continuity and it was fine. Relay is good, I swapped it with the horn relay and the ac relay from another truck that the ac works. Not sure if I’m missing something easy or if PCM is bad. Would just like to hear the thoughts from someone that knows more than me.

Thanks

4 Replies

SIDEWINDER313

MEMBER
3 POSTS

Never mind I have found the issue and fixed it!

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Wednesday, June 14th, 2023 AT 6:58 PM

BRENDON S

MECHANIC
653 POSTS

Hello SIDEWINDER313,

Glad you got it fixed. Can I ask what the cause was? It may help someone in the future that comes across this thread.

Thank you,
Brendon

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Thursday, June 15th, 2023 AT 6:48 AM

SIDEWINDER313

MEMBER
3 POSTS

I read something that said the plug on the back of the compressor was for rear A/C. I don’t have rear ac in my truck and the new compressor I bought didn’t have the plug, I figured it was no big deal. After replacing pretty much every other ac component, I learned that I need that I needed the plug since it was a high pressure cut off on the compressor and had to buy it separately and install on the compressor myself. After that it works perfectly.

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+1

Thursday, June 15th, 2023 AT 10:39 AM

BRENDON S

MECHANIC
653 POSTS

Hello SIDEWINDER313,

I see. Glad you got it fixed and thank you very much for sharing that information with us. It will help others in the future.

Thank you,
Brendon

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Thursday, June 15th, 2023 AT 11:16 AM