I recently replaced both belts on my 98 Toyota sienna. There was a squealing noise. The old belts did not not look too bad. What I was concerned with was during previous drives when it was wet and I went through a puddle it seemed that the steering wheel locked up as to lose the power steering and I was thinking maybe the power steering belt was slipping. But now I notice a squeaking or clutch or tensioner noise when I turn on the air conditioning goes away when I turn off the air conditioning goes on squeaking when I turn on the air-conditioning again .

So can I safely assume that it’s probably the clutch to the air conditioning pump?

Squealing only when it runs could be either a bad compressor bearing or a bad belt. Have you checked the belt tension? It might have been a 20 year old belt that just looked new. Belt dressing can help if a belt is slipping.

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Do you feel any change in the steering response when you turn on the A/C?

I agree, it could be either the compressor, the clutch, or a loose belt that slips under load.

The first thing I'd check is the belt tension and deflection, and general condition.

Belt dressing has always been a messy, temporary fix, for me, so I stopped using it.

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Quote
RAMd®d
Do you feel any change in the steering response when you turn on the A/C?

I agree, it could be either the compressor, the clutch, or a loose belt that slips under load.

The first thing I'd check is the belt tension and deflection, and general condition.

Belt dressing has always been a messy, temporary fix, for me, so I stopped using it.

This x2, except belt condition. You said they were new.
Check belt tension and deflection (adjust per spec., you can find it online ) if all is well, buy an Mechanics Stethoscope [www.harborfreight.com]
Use it to check the other parts listed including the tensioner. It’s cheaper and easier than replacing parts just on a hunch.



Edited 1 time(s). Last edit at 07/31/2019 12:00PM by Carm.

Belt dressing is just a temporary fix. However, if the squealing stops after spraying some on the belt then it would seem to verify that the problem is a somewhat loose belt.

usually the belt will squeak once it becomes varnished from too much wear. new belt is the answer.

if it is the problem to begin with.

tensioner does sound suspect.

New Belt

Scotty Kilmer doesn't recommend using that belt spray stuff.

I have the harbor freight stethoscope thingy, will give a listen using that and a piece of solid dowel to see if I can narrow the location.

thanks for the help

Most serpentine belt vehicles use a spring loaded tensioner, that's the first place I'd look. They are a replaceable part and they do fail. Often they'll get a little rusty at the pivot and not move as freely as they should. The spring can also break or just weaken over time. Usually the tensioner will come as a complete assembly that just bolts on.

Also check that idler pulleys and other belt driven components are turning free and smooth. Don't use belt dressing, especially not on a serpentine belt.