A/C Squeal? Need Help

Please help, New member here but ive been lurking :surprise:
I have a 3000gt base, when I start the car it squeals just a little bit until it is warmed up then stops but when I turn the ac on it squeals constantly I've replaced the idler pulley, tension pulley, serpentine belt, and alternator (unrelated problem). Is there a way to check the oil in the ac compressor or do you guys have any ideas what it could be? And there is no grinding noise so I don't think it is bearings and visually there is no wobble.. Thanks in advance..
Ttmarsh19

I had that problem for a long time. I ended up replacing the belt and the idler pulley and tightening the hell out of the belt. Now it doesn't do it anymore and I feel sane again. The first time I did it it wasn't tight enough and started to make the noice a week later so I made it much much tighter. However because of the tension I had to put on the belt to get it to stop squaling I've been keeping a spare belt in the car just in case it breaks somewhere.

Been there done that. Eventually it would never stay quiet. I ended up replacing the compressor and it's been ice cold and quiet ever since. The problem is as the compressor goes out it gets harder and harder to turn. Tightening the belt tighter every time it squeals will cause your idler/tensioner pulleys to get extremely hot and eventually go out from too much friction, if your compressor doesn't go out first. Tightening the belt that tight can also effect your Alternator by getting it very hot. The bearings in these things can only take so much heat.

Keep in mind the harder it is for your compressor to turn that your engine has to work harder. You will lose power and gas mileage. You can pick up a good compressor from a wrecking yard pretty cheap.

I got a similar problem, there was a metal noise, more like a grind, it was the compressor plate/rotor, combined with lots of carbon buildup, the nut was loose and it touched the compressor housing on every rotation, I tightened the nut and also checked the clearance, no more noises.

http://i.imgur.com/6h0hiBg.jpg?1

http://i.imgur.com/nlGZt4S.jpg?1

I had the exact same problem! I took all the belts off and looked for play and spun them to feel for resistance/listen for noise. My idler had a little play so I replaced it. My alternator bearing was making a little noise when I turned it by hand so I replaced that (think that was my noise at cold idle). I also replaced the AC belt and tightened it so spec (pretty damn tight).

No issues now! I used to be able to run the AC sometimes at low loads but climbing a hill or giving it has caused it to make the noise real bad. Think the belt was slipping. Think the alternator was making the squeaking noise at idle.

So bottom line, turn them all by hand and check the tension.

When the compressor starts to lock up it will cause the belt to squeal as the compressor pulley is no longer turning so the belt just gets dragged along the pulley hence the squeal. If you find yourself having to over tighten the belt then you either have a bad pulley somewhere or a bad A/C compressor. Most of the time it is due to either the belt being too loose or the compressor is locked up. If the belt is too tight then you can damage the compressor more along with the pulleys and the alternator. Follow the manual for the correct tightening procedure.

Does it squeal when you have the A/C on and not when you have it off? The A/C clutch was going out on mine causing the squeal. I just replaced the clutch on the compressor. That cured my squeal.

Marshall