Hello all!,

I hope this finds you all doing well. I had a question on my 99' Cherokee 4.0L. I just hit cold weather here recently in MI, and have noticed when I turn the heat on, it squeals pretty bad, until i shut it off, get to atleast 10-15 mph, then turn it back on and it runs fine. Did the same thing with the AC. Anyone have any ideas, things to check, a fix? Anything would be greatly appreciated.

 

There is a good chance your a/c compressor is starting to seize up.

 

It could be your alternator. It could be that your belt is loose and slipping or just old and needs a better one. I'd get a Gatorback and make sure its nice and tight before buying any other parts.

 

I have the same issue on my '97. It happens when the jeep has been sitting and I first start it and then turn on the AC. If I turn the AC off and give it a minute and turn it back on it doesn't do it. I thought it was the belt but it shows no sign of wear or glazing. So I am very interested in the responses to this thread.

 

Mines the same

We went from a/c to using heater in a couple days.
I know belt dressing is a no no on a serpentine belt but it worked instantly. Temporarily though,
New belt time
It's on the list.........

 

mine did the same,while it was squealing,i tightened the belt until it stopped

 

I have a 2000 and am plagued by the same thing. I keep tightening the belt and that works for a week or 2 then it just loosens up again.

I want to fab some kind of deflection pulley near the balancer that wraps the belt further around the crank pulley. I feel the belt just doesn't have enough contact with the crank pulley.

 

Chances are that squeal is a bearing starting to fail. In my case it was the alternator. The water pump is also a possibility, as are the idlers. Not likely the A/C compressor unless the A/C is on.

Remove the belt and check all pulleys for roughness while rotating and end-to-end or side play, there should be none.

When the bearing fails, and it will, the belt will snap and you'll be stranded. Happened to me.

 

I know in my case, it's belt squeal, 100% sure. The battery voltage drops when it happens because the belt is slipping on the pulley.

 

Re-tighten the belt and go from there. What ever you do DO NOT spray it with belt dressing. That stuff is made for V belts and not for serp belts. Putting it on a serp belt will only make it worse and can cause the belt to fail prematurely.

 

If your voltage is dropping I would suspect the alternator. Belts don't just start squealing. If its squealing (means the belts going faster) and the voltage is dropping (alternator isn't keeping up), then the bearing for the alternator is going out.

 

It definitely has something to do with the A/C compressor. If it was a loose belt it would squeal all the time. If it was the alternator or other pulley it would not stop immediately when the A/C is shut off. Its like the compressor gets stuck and need the belt moving fast enough to free it. Mine does it but only after it sits over night. For the rest of the day it is fine.

 

It's too much load on the belt. It squeals when I first start the engine with the A/C on with high ambient temp. The belt squeals like a stuck pig. That's when the volt gauge drops. If I cycle the A/C off and on a few times, everything work normal. The squealing is coming from the belt.

 

Have you tried to tight the belt as I mentioned in my earlier post? I had the same problem and all it was is the belt needed to be tightened a little more. The ac does put a large load on the belt and can cause the alternator not to spin fast enough causing a low charge.

 

Once I re-tighten the belt it will be quiet for a few weeks but it seems like the belt just stretches back out after that time.

It just seems to me like the serpentine belt routing could have been thought out a little better on this engine. There's not enough contact with the crank pulley.