Hello - I have an H2 Hummer 2007 with 6.0 gas engine.
The AC pump is run off it's own belt, not the serpentine. The belt broke about a year ago and was replaced. Now a intermittent belt squeal started, but not sure which belt or why. Had a guy look at the tensioner and he thought it moved a bit too much and was a bit rough so he replaced it and the belt.
He also noticed, and showed me that the AC clutch was engaging and disengaging very fast, like every second or two and it would spin about a quarter or half turn and stop again. AC and defrost were off. Unfortunately he removed the AC belt so it wouldn't keep doing that and would remove the squeal if it was the source as I lived a hundred miles away.
Afterward, of course, no squeal. But now I wonder what this intermittent clutch action could be caused from. Do I really need a new compressor or could it be a relay or something electrical? Electrical ghosts are not uncommon on this rig.
Does anyone know? Don't really want to replace the compressor if it could be a $20 relay. If it is possible it is a relay, is there a way to test it? Or is there something else I could do to determine the real problem? Putting the belt on is a major pain in the butt.
I appreciate any advice. Thanks.

 

First check the refrigerant charge and make sure its not low, if not then jump the low pressure switch (common failure component), from there look for a loose wiring connection.

Neal

 

Squeal is also often caused by wet belt or wet clutch, as after blasting fresh water to clean out the rad. Very sensitive on the H2.

wash it or submerge it lately when the issue started?

 

Thanks. Yes I am aware of that issue, and this isn't the case.

 

Thank you. I did this when the belt broke a year ago and it has worked fine until now, when the squeal started. I'm trying to save a 250 mile round trip to have it serviced/diagnosed again. I'm hoping that what I described might diagnose it as a probable or certain electrical or relay issue, or probable or certain need to replace the compressor. Do you think what I described could be caused by just a refrigerant issue? I don't have a gauge, I'd have to buy a can with one. What if I tried to jump the power at the relay to see if the pulley moves in and out, would that prove anything one way or another? Thanks again.

 

Oops. I failed to identify who's post I was replying to. The "I'm aware" reply was to legerwn and the longer reply with questions was to finall. Thank you both.