Since I've had my AC recharged, I've noticed a bad squealing noise when I'd put the fan speed on 3 or 4. Almost always I'd be able to get away with running it on 1 or 2 without this problem with a few exceptions (either turning the wheel too hard or something like that). I decided to replace my serpentine belt to fix the problem and it's only gotten worse. I can't run the AC now without it squealing or chirping. I thought it might have been the idler pulley (a shot bearing maybe), so I replaced it and it still happens. My mechanic told me since my electric fan isn't kicking on when the AC compressor is turned on, its causing the compressor to build up more pressure, making it work harder and putting more stress on the belt, making it squeal. The only thing is that it does this when the engine's cold too. But I've overridden the electric fan with switch, so that I can manually control it. The problem continues. I don't know if one of the other pulleys is shot, or if the compressor is bad. It blows cold air fine but I don't really know much.

I recorded some videos that might help in diagnosing the problem, these are the links



Here are some pictures of the belt and the compressor as well:

 

Have you spun the compressor pulley? Find out what the bearing are like.

 

I've spun it, but I don't know what worn pulley feels like. It feels normal to me

 

Have you checked the other pulleys as well? Spin them, they should keep spinning for little while. Nice and smooth like. No grittiness. Think butter.

 

I'll have to take the belt off tomorrow and update you then, assuming the pulleys are fine, could the compressor be pulling to much electricity and making it work too hard. When I got the ac fixed the clutch relay was blown, maybe that's part of the problem?

 

If the squealing starts to continue no matter how fast/slow you're going, check your belt for a line of wear, then i would consider a water pump going bad... the propeller inside tends to start grinding away as they get old...

 

When I drive it it's fine, no issues with the squealing, if it was the water pump wouldn't I hear it whenever I gave it gas

 

makes no sense to me,??

 

Yea I agree, there are tons of 00 and 01 XJs. The E-fan is programmed to come on at certain PSI and does not run all the time like the previous models.

I don't think the mechanics theory holds any water or else all us 00 and 01 owners would be having problems. Try again Mr.Mechanic man.

 

Took screen of this after a quick search here on the forums .
Mechanics theory is right to a degree . Fan is supposed to come on with AC turned on once it reaches higher pressures . If the fan isn't working then at idle or slow traffic etc your pressures will get real high and can ruin the compressor due to excess heat and if it's high there will certainly be more resistances with excess pressure . I would hook it to A line set and see if they ever kick on when high side reaches 270-330

 

That's 97-99. The operation changed in 2000.

See here, CCKen post

https://www.cherokeeforum.com/f2/coo...nction-133903/

 

Ok my bad didn't see the year of his Jeep mentioned .

 

No problem my man. It the thought that counts. :-)

 

The only thing I've noticed that may contribute to the problem is that when I put the belt in, the voltage on my dash was reading 12 volts for about 30-45 seconds after I started the car, before it would go back up to the normal 13.5 or 14. Maybe the alternator pulley is bad? It drops when the AC is on, but I feel like that's because the compressor pulling too many amps, causing the belt to slow down and not letting the alt charge the battery. Don't think its the water pump, would't I be having overheating issues if it was that? The blown relay from the AC makes it seem like the culprit.

 

The first thing you should always do with a belt squeal is to get a Krikit belt tension gauge and set the belt tension to 140 to 160 ft lbs (or 180 to 200 ft lbs for a brand new belt that has never been run). You can sometimes get one from Napa auto parts stores, or you can order one from Amazon.

Often the squealing is caused by a loose belt. They're supposed to be tighter than most people think. You cannot tell if the belt is tight enough by twisting it with your fingers unless your fingers have somehow been magically calibrated to 140 to 160 ft lbs. Otherwise you're basically just guessing.

If you still have a problem after making sure the tension is correct, then start looking at something binding up.