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Compressor clutch not engaging - why??


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OK, I've got a '97 STS. The compressor clutch is not engaging, and from what I've learned so far, the PCM is not telling it do enage when it should. I learned this from Guru's post here:


I am not sure if the information that bbobynski provided in that post applies to me or not... but here's what I see with my car.

First, obviously, is no cold air!

By looking at the compressor, I see the clutch is not engaging.

A/C comp fuse is good.

I do not see any DTC codes except a couple of irrelevant ones.

When performing the tasks in Guru's thread, when in the PCM section, I see on the climate control disply, only the "AC" and "AUTO" lit up above the front defrost button, an arrow above the "MODE" button and the rear defrost light is lit. The front defrost light is NOT lit (which, accodring to Guru, is indicating that the PCM is not telling the clutch to engage, even though it should (yes, the a/c was on when I went in to the OBD.) Also, I don't seem to have an ACP section, as Guru refers to.

I do have the GM service manual for my car and it has a troubleshooting flow chart that instructs me to check the a/c relay. How do I do this? I see it in the fuse box and it seems to be taped together to an adjacent relay. Do I remove the tape and the relay just comes out? I don't know the pin labels for the relay and don't see them in manual.

Can someone please give me some direction. I live in Louisiana and it is starting to get HOT!! Temperatures are already in the 90's with heat indexes in the 100's



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OK, the flow chart has taken me past the relay and to this:

"Check voltage at pin 'A' of compressor clutch"

I can not seem to find where pin "A" is or whether or not it is even accessible. Not only that, how do you check the voltage on one pin?

Any help would be appreciated.



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The Cadillac systems are goofy....

You have to clear the AC codes after repair. If not, it stays in turned off mode.

I think the service manual is asking you to measure voltage at the pin A to ground. Pin A will be at the front of the compressor clutch.

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