'01 Duramax A/C compressor no worky

[Tynee]

Anybody got a good link for trouble-shooting my buddies '01 duramax A/C compressor? He said he took it to get it charged, it was a little low, so they did indeed charge it, and checked for leaks, but found nothing. When it quit blowing cold again a couple days later, he took it back to them, they put the gauges back on, and the pressure was fine, but the compressor won't engage.

I'm headed out now to see if he's got voltage to the compressor clutch, and maybe jumper the low pressure switch to check that out. Any other suggestions? What else would make a compressor with a good charge not engage?

[bwood]

There is also a high pressure switch on the back of the compressor and sometimes one on the liquid/high side line. If they overcharged it, maybe its keeping the compressor locked out. Also make sure the switches/buttons on the controls are working. There is also a relay for the compressor clutch, they have been known to fail.

[mbgmike]

Originally Posted by Tynee

Anybody got a good link for trouble-shooting my buddies '01 duramax A/C compressor? He said he took it to get it charged, it was a little low, so they did indeed charge it, and checked for leaks, but found nothing. When it quit blowing cold again a couple days later, he took it back to them, they put the gauges back on, and the pressure was fine, but the compressor won't engage.

I'm headed out now to see if he's got voltage to the compressor clutch, and maybe jumper the low pressure switch to check that out. Any other suggestions? What else would make a compressor with a good charge not engage?

If the pressure is good sounds like you need a new compressor. do not waste time on rebuilt ones. The compressor can still turn and not work.

here is a link to GM clutch diagram

You may want to look here to http://aircondition.com/tech/

[Tynee]

Originally Posted by mbgmike

The compressor can still turn and not work.

here is a link to GM clutch diagram

I don't know that the compressor is or isn't turning, the clutch won't engage. It's not getting a signal to engage, though.

Fuses are good, relay is good. No obvious problems with the control panel. jumping the low switch didn't do anything.

Any tips on checking the other two sensors?

EDIT: Scratch that, I DO know now that the compressor will turn. I jumped 12V to the clutch and it engaged. I'm sort of at a loss why it isn't getting a signal to run, but it's not.

[bwood]

If I were at the same point, I would find a diagram for the AC controls and check out the AC relay and terminals. Make sure the relay is getting the signal to come on. I don't have a diagram for your 01 though.

[Tynee]

Thanks for the input, guys. I gave it back to him yesterday afternoon. Needed to do some work on my own truck, and then needed to spend some time in the crawl space under my house. Too much to do to spend any more time after all the stuff that I knew or could figure out easily.

I think he's going to drop it by a dealer that is convenient to his office.