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A/C Issue Electrical

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Old 05-14-2012, 11:11 PM
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Default A/C Issue Electrical

The clutch stopped engaging on the truck last month. So heres what ive tested so far.

1. Check system psi , its fine

2. Jump low pressure switch nothing...

3. Check all fuses. There good.

4. Jump the compressor with leads from the battery. Clutch engaged hmm!

5. Swap AC Relay with known working fuel pump relay. Nothing....

6. Ground out AC Relay pins. Clutch comes on. WTF!

7. I swaped hvac controls with a known working unit. Still didnt work

Could it be a bad spot in the pcm? Ive read its possible since it has the final say so on engaging the clutch.
Old 05-16-2012, 05:11 PM
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could very well be a blown compressor make sure it still spins freely all you need to do is we're the belt goes on the pulley can turn by hand your good if it docent most likely its toast
Old 05-16-2012, 05:14 PM
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I've had very similar issues...the last couple of years.
It doesn't do it all the time.

Old 05-16-2012, 08:15 PM
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what and where is the "pcm"
Old 05-16-2012, 08:34 PM
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Had this problem last year. Check pressure switch connector by compressor for 5v and ground.
Old 05-17-2012, 08:44 AM
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Originally Posted by twolow02fransen
could very well be a blown compressor make sure it still spins freely all you need to do is we're the belt goes on the pulley can turn by hand your good if it docent most likely its toast
Tried it it wont spin.

Originally Posted by TXSZ66AVLANCHE
Had this problem last year. Check pressure switch connector by compressor for 5v and ground.
If it wasnt getting the rite power source and ground. It wouldnt have worked when I jumped the relay.
Old 05-17-2012, 10:08 AM
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Originally Posted by TXSZ66AVLANCHE
Had this problem last year. Check pressure switch connector by compressor for 5v and ground.
A friend had this issue a couple of years ago and was driving him nuts too.
He ended up replacing one of the pigtails and it solved the problem.
Lemme see if I can find out to which switch it was...
Old 05-17-2012, 10:23 AM
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Originally Posted by BuiltNotBought
Tried it it wont spin.



If it wasnt getting the rite power source and ground. It wouldnt have worked when I jumped the relay.
Mine worked when I jumped the relay, but would not work when turning the ac on from the control head. No 5v reference signal to the pressure sensor by the compressor, break in wires was about 6" back from the connector.
Old 05-17-2012, 12:44 PM
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Originally Posted by TXSZ66AVLANCHE
Mine worked when I jumped the relay, but would not work when turning the ac on from the control head. No 5v reference signal to the pressure sensor by the compressor, break in wires was about 6" back from the connector.
Ill double check. But I took all wire from compressor all the way up to fuses out of lume and inspected. They were fine. We are talking about the plug behind the compressor right.
Old 05-17-2012, 01:41 PM
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No, the pressure sensor on the line BY the compressor, not the clutch wiring.


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