I have a 99 XJ 4.0. When I turn my a/c or heater on the belts squeal very loudly. I have tried tightening the belt but I'm not sure how tight this needs to be. I am hoping this is the issue but what else could it be? I've noticed that it only squeals when the compressor kicks on and the voltage meter shows a slight drop. When I press the gas pedal and increase RPMs then the squealing stops. Could this be a bad alternator or bearings bad in the compressor and if so how do you check?

 

I am thinking your belt is loose..

Ant...

 

How old is the belt?

 

I am not sure. It doesn't look that old.

 

When in doubt change it out.

 

Try to check if the clutch mechanism on the a/c compressor is working properly. I dealt with this same issue and found that the clutch tends to freeze, so instead of paying for a new compressor or rebuild kit I just got an a/c delete pulley. If you don't use a/c it's a quick and inexpensive fix.

 

I have this "canned"

Soaping Belt


Tight, tighter, tightest the darn new belt would still chirp.

Finally in desperation I went out there with a bottle of Dawn dish soap and the garden hose. Idling, I got it wet, then squirt soap on both sides, rinsed some, and soaped a little more. Let it idle a minute all soapy. To end, I ran the hose slow on it running for a couple minutes. Bingo! That solved it. There was some sort of coating on the new belt? Idk.

I normally run my belt as loose as I can, and still have the alternator not slip with the blower on high, and lights on brights. Puts less strain on all the other bearings. Radi pointed out a cool tip. After it might have been slipping, (voltage has been low), see if the Alt. pulley is hot. I want to go back and loosen it a tad now.

 

Yeah the old soap on the belt is tried and trued. But if you have no idea of the age of your belt and hoses change em out.