More A/C issues

[71chevmal]

Got the actuator changed but now there is no A/C at all. I do HVAC for a living so I didn't think I would have to much issue nailing this down. It seems I have two issues. The first being that I don't seem to have a call for cooling even when I have both front and rear units on and turned down all the way. I checked for power at the compressor plug and there was none. I jumped out both pressure switches just to be sure. Then I pulled the relay and jumped over that. That's when I got power down at the compressor. The second issue is that the clutch doesn't appear to pull in. I have a set of gauges on it and the pressures never change. Also, if I jump the relay with the car off, I think I should be able to hear the clutch pull in and I don't. I've checked all the fuses and they are all fine. Anyone have any suggestions? The dual zone control head lights up and appears to work. I know they go bad but I don't know what it looks like when it does. And even if that was the problem, the clutch issue seems odd. Changing the clutch looks darn near impossible without pulling most of the nose. Is it a situation where you just change the whole compressor? This truck is giving me fits lately so any suggestions are welcome. Thanks..

[brcidd]

Can you feel the relay energize as you plug it in and out of its socket when a/c is requested? If so and you have already bypassed the relay and clutch still does not pull in, then the most probable cause is there is too much gap between the clutch plate and pulley face- due to wear of the two surfaces. this is very common on nippondenso compressors used on all GM C/K trucks including yukons 5.3L and 4.8L engines from 2001 model yr and up.

To test the "too wide gap scenario"- have a/c rquested with engine running and tap on front of compressor with a hammer handle-(from underneath) if clutch snaps in, then you need to remove 10mm bolt and wiggle off clutch from splined shaft, then watch carefully for shim(s) to fall out from behind clutch plate- remove the thickest shim- and replace clutch driver, and 10mm bolt and be happy.

Yes it is tight in front of pump- but is very doable- I've done dozens this way- easiest to remove splash panel first.

You've never stated the model yr or mileage-- this scenario usually happens at 150,000 or more....and 2001 or newer...

[71chevmal]

Thanks. I will check those out ASAP.

I thought I had my truck in my signature but I guess not. Sorry.

It's a 2004 Yukon with 176,xxx miles.

I swapped the A/C relay with the high beam relay and the high beams still work and the A/C still doesn't so I'm thinking it isn't that.