"squealing sound" from engine compartment (espec. when A/C is on)
 

I have a 99 cherokee XJ with the 4.0 6 cyl. It makes a "squealing" sound from the engine area (from the pulley area) especially when its raining or when the Air Conditioning is turned on..... I installed a new belt, tried to adjust it (but doesnt seem to help, maybee the belt tensioner is bad?) and the A/C compresor is new (about 1 1/2-2 years old) so I don't think its the A/C compresor, it seems to come from where the belt tensioner is or power steering pump area......What do I need to do to fix this?? Its so irritating......

Phil :w00t:

it is the A/C compressor its the bearings, mine does the same thing, if you dont wanna replace them buy some spray to spray on it and it will go away for a while

Mine does the same thing. Where do you spray the lube to make it stop the noise?

on the compressor where it turns the belt

You mean behind the pulley? I have some lithium grease, will that work?

also if the belt is old it may be glazed, check the tension on the belt and adjust is more then 1/2 of play when you press on it. but mine occationally chirps engaging.

Don't spray anything on a serpintine belt, I would just replace it, if you sprayed anything on it and for what ever reason on a 4.0 the tighter the better (to a point) with new belt.

yeah its the pully, mine has a new belt onit and it still squeels

i thought they all do that

Sounds like the Belt needs tightened up a touch

Mine is also doing it. If I shut the A/C off for just a sec and turn it back on it stops.

it sounds more like a belt than anything else change it first

mine does it. my belt is new and tight. my a/c is off at startup and it does it almost everytime.

like i said everybody its the pully on the compressor, ill bet all of yall if you go spray somethin on the pully like WD-40 or anything like that then start up your XJ it wil do it for a second then stop for a while, ill put money on it

Long answer to your thread.
Well let me put my 2 cents in on this.
I get tired of hearing it's always the AC pulley or bearings. I also have been fighting with the squeeling during damp weather, putting the vent controls on window defrost, or using the AC. I also replaced the AC unit with a used one which seemed to stop the sound for a little while, but the noise came back.
I wrote in other threads, my friend who works as a mechanic at the jeep dealer told me to get rid of the serpentine belt with the newer diagonal cuts across the belt and replace with an AC Delco type with straight grooves. These other belts are prone to make the belt squeel. I did replace the belt and the squeel did dimenish for a while, but still came back during rainy days and using the defroster setting. One day the squeel turned into metalic grinding, which turned on my battery light. I figured it was the Alternator Bearings grinding. I had a spare used Alternater and took it to AutoZone to check out weather it was good or not. Alt. OK. Since I work part time at Sears Auto Center, and had to work that night, took it with me. While pulling it in a bay to have another installer look at to verify the grinding noise was fom the alternater, the POWER Steering pump went out. Sprayed fluid all over the engine. We replaced the pump resevior and pulley with a new one. WOW the squeeling noise went away and I am able to use the defroster and AC without any more noise. There have been a few threads about the powder steering pumps being a problem and creating the squeeling noise as the bearings go bad and slow down the speed of the belt. Of course the engine is still trying to spin the belt at a high speed and the belt squeels. Look at your power steering unit before condeming the AC unit.