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A/C Compressor Issues

bigred88

bigred88

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So, after an extensive forum search, I think I have an idea what's going on, but I'm still not quite sure.

When I turn on the AC, the belt squeals something awful. I replaced the belt, made sure it was tight, and it's exactly the same. When the AC is off, there is no noise at all.

A few months back it would squeal intermittently, but would work fine (run for 30 seconds, chirp for a second or two, repeat). Last summer the condenser was replaced and the whole system was switched over to R-134. I haven't checked the charge, but it should be full.

This all leads me to believe that the compressor is probably frozen. Any way to make sure before I drop the money on it? They're pretty pricey, I'd hate to do that when it was something else.

Also, as I was changing the belts, I noticed the power steering pump was a little loose (not tension wise, more like I could shake it around with everything tight). As I got to looking at some diagrams, it turns out the bracket is missing off the back of the power steering pump. Is it possible that without this bracket the pump is sitting at a wrong angle (even just slightly) and pulling the AC compressor wrong, therefore causing it to fail? It is the original, 22 year old 175,000 mile compressor, so for it to fail wouldn't be a complete surprise, but I don't want to put in a new one just to kill it.

Thanks in advance for any help.
 
Sounds like it is froze up inside the compressor.
With the engine off and the key off try to turn the furthest outside portion of the AC clutch with your hand. You should be able to turn it easily.
If you cannot turn it then the compressor is locked up and will need to be replaced.


The filter/dryer and the orifice tube will also need to be changed when you change the compressor.

The power steering belt being out of alignment will not have any bad effect to the compressor.
 
If the belt that drives the power steering pump is not the same as the one that drives the compressor, then that should have no effect.
Note which way the pulley turns when it is running, turn the truck off and remove the belt.
Turn the key on, but do not crank the engine.
Turn the AC on, and then try to turn the compressor pulley the same way.
You should be able to turn it. It may be stiff, but should turn with some effort. It may get too hard to turn after a short time, but with that many miles, I suspect you will be able to continue turning it with effort.
If its locked, bad compressor.

J.
 
The compressor clutch can fail without the compressor itself failing. If it's just the clutch, then no need to replace the orifice tube or filter/dryer. Otherwise, bust out your wallet for a complete system flush. :haha:

A couple days ago I fixed an MRAP with a blown up compressor. It spread compressor chunks/dust/crud throughout the entire system, minus the evaporator side. Thank god. It took almost 4 gallons of the flush chemical to get the condensers douched out and clean enough to recharge. Replaced the filter dryer as well, and had 44* vent temps. That made for one happy crew. :bow:

1151's (humvee's)always seem to loose just the clutch while the internals of the compressor itself are fine. Which is a good thing....With all the up armor on the 1151's, getting at all the hoses and components is a bitch. :crazy:
 
I tried turning the front of the clutch, and it turns, just not easily. I haven't checked if it cools, it squeals so bad I didn't want to leave it on long enough to find out.

I had someone turn the truck on while I watched the AC, and the belt (and clutch) spins fine with the AC off. When the AC is turned on, it spins (and the clutch engages correctly) for about a second, then the clutch seems to meet some resistance. It still spins, but much slower. It slows down the same time the noise starts.

I'll drive it around and see if it cools.
 
It blows cold, but not as cold as it used to. Definitely colder than outside air or just set on vent.

Gotta piss off everyone in the neighborhood when I have it on, though...
 
On the humvees, when the clutch fails, the front of the thing get's so frickin hot that all the paint on the pulley/clutch get's cooked off and turns a rust brown color. If yours is still cooling, then like brit said, the pump itself hasn't failed yet. The clutch could be on it's way out though. Run it for a bit, 15-20 minutes at least, then touch the front of the pulley/clutch, or spray some water on it, if you yelp or the water sizzle's, the the clutch is going. If you let it go too long, the clutch will seize, which will smoke a belt right in half within minutes and could hasten the compressor blowing up. Good to catch it now...you don't want to pay for the new compressor AND filter/drier, orifice tube and system flush.
 
So it sounds like I should just replace the clutch, and see what that does. Thanks for your help, I'll post back if that doesn't fix it...
 
You need to figure out what is squealing for sure.
Crank it up, turn on the ac, and when it starts squealing, spray some water on the belt away from the pulley. If it quits for a second, the belt is slipping, and you need to find out why.
If not, then its probably the clutch slipping, and it needs to be changed.

J.
 
KidJethro said:
Easier to just replace the compressor.
Click to expand...

Easier, maybe, but cheaper?

As far as knowing what is squealing, I'll try spraying water on the belt, and see if that helps. I can't think of a reason why the belt would be slipping, though (except for there being too much resistance coming from the compressor- that's the only thing I can think of). I just replaced them, and they're as tight as possible.
 
It only squeals when the AC is turned on, so I'm pretty sure it's the AC... just replaced and tightened all the belts a few days ago though, so it isn't just a worn out or loose belt.
 
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