A/C compressor question

[extra-medium]

Last fall I asked a question about running E85 and it sounding like I had a massive supercharger. Since I have quit running the E85 but noticed that it still has a whine like a supercharger. It will only whine when the a/c compressor is running/engaged. I was hoping that I don't have to replace the compressor, or maybe the clutch on it, but I can't think of what it could be.

 

[Donystoy]

As long as the compressor clutch is not slipping the problem likely is in the compressor itself. The clutch bearing is only spinning when the A/C is not engaged. Is the A/C cooling properly? One way to check is to see if the larger suction line is cold going into the compressor. Watch out for the belt!
I have seen automotive A/C compressors make noise when they are low on refrigerant.

 

[D Hook]

Might want to check the cheaper components first also. Turning on the A/C compressor can load the belt and the belt idler pulley, causing them to make a noise also. Have you changed the belt recently? Sometimes a new belt will set up a new noise you've never heard before.

 

[extra-medium]

The a/c cools like a champ no matter what the temperature is outside. I haven't been under the hood much due to lack of funds and nothing really going wrong. I will check and see if it has enough refrigerant, I would assume so since it cools really well during the hot Utah heat. As for the belt, I haven't checked it since I haven't been under the hood much except to do an oil change not too long ago, and I did that pretty quick since it was freezing out.

 

[n2audio]

I see this is a couple mos old but I thought I'd offer my recent experience anyway.

My 03 aviator makes the same noise. Really loud power steering pump or big super charger is how i've described it to others.
Took it to a good tech and he tried to pinpoint the whine using a stethoscope. Believes it's the compressor - internal. His only suggestion was to wait for it to break and replace it.

During standard a/c service found it was low on r134 by more than a pound.
He also offered some high dollar synthetic a/c oil he thought might prolong the life of the compressor which I agreed to try.
Immediate results showed no appreciable improvement in the noise -- maybe it will get better as the lubricant circulates - the work was just done today.

So I would say be prepared to replace it at some point - the sooner you can be prepared, the better.
My shop's quote was right around $800. I think that's quite a bit less than the typical shop. A relative had one done on his v6 last summer and their quote was about 1200.