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.

 

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

 

I've had very similar issues...the last couple of years.
It doesn't do it all the time.

 

what and where is the "pcm"

 

Had this problem last year. Check pressure switch connector by compressor for 5v and ground.

 

Tried it it wont spin.

If it wasnt getting the rite power source and ground. It wouldnt have worked when I jumped the relay.

 

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...

 

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.

 

No, the pressure sensor on the line BY the compressor, not the clutch wiring.