Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

AC Noise when clutch engages

Hello, I have a 2006 Toyota Sienna with approx 64K miles. Recently, I am hearing a squealing noise when the AC clutch engages (AC is working fine and blows very cold air). When AC is off for when the clutch is not engaged - no noise at all… I have been getting alot of different answers as to what it could be and it is very confusing… to me - it sounds like a clutch issue and I have seen videos on how to take apart and see if it is a bearing or bad clutch. I did pull the belt and checked the pulley - it turns freely and there is no bearing movement. Just looking for some honest opinions on my situation and how I can go about getting it repaired without replacing the entire compressor and other expensive parts at a cost of $1,200 bucks…


If the compressor clutch were slipping, it would start to get very hot and start smoking. And if it were the bearing, it would make noise whether the AC was on or off.

It sounds like the compressor itself is starting to fail.


When you ‘‘pulled’’ the belt…did you replace it ?
You could easily have an old belt that is finally getting hardened or compressed a bit and can’t quite keep up with the load demand.

If it were the bearing you’d hear it all the time , yet it could be internal in the compressor.
Is it a scaping metalic sound or a squeek ?

Try a new belt first.

If that car has the original belt on it then that might be the first suspect. It would be 9 years old and rubber hardens with age.

With the engine running and A/C operating and making noise, spray a little WD-40 on the belt. If the noise instantly stops replace the belt like OK recommends…(The WD-40 trick is only temporary…)

To clarify, the clutch bearing would only be heard when the A/C is off. When the A/C is on, the clutch turns with the compressor. Make sure the belt tensioner is working right, then put on a new belt.


Explain how the clutch bearing would only be heard when the AC is off?


When The A/C is off, the compressor is not turning. The sheave is turning and the clutch is stationary (just look at it to confirm this). This is when the clutch bearing is active and would be heard if it were failing.


When the AC is off the pulley and bearing are still spinning. When the AC is turned on, the clutch disc on the front of the pulley is pulled into the face of the pulley which is still spinning with the bearing. The clutch disc is attached to the shaft of the compressor which spins the compressor.


I believe what you call the “pulley bearing” is what I call the “clutch bearing.” We both know how it works, just using different words.

If it is the compressor and not just the clutch, I would suggest getting it replaced before it fails. If it blows apart, it will spew the metal filings through the system which will require additional cleaning of the system to repair it. In my humble experience anyway.


If it is the compressor making the noise, it’s too late.

The system will still need to be flushed out before the new compressor is installed.


All, thanks for your comments - very helpful. I am going investigate further. The noise is a scaping metalic sound - but I saw a u-tube video where it was the same exact sound and it was the pulley bearing that was bad - but you could only hear it when the clutch was engaged. I am going to wet the belt when the engine is cold and listen for the sound after I drive around for a while. If it is the compressor - can I just replace the compressor/clutch without replacing anything else - is that a bad idea?

Thanks again.


If you’re going to replace the belt, I highly recommend a belt from the dealer. When I replaced the timing belt on my Camry recently, I replaced the original AC compressor belt with a Gates belt. Ever since then . . . no matter how I adjust it . . . the belt initially squeals when I engage the AC. The Gates belt has a different composition than the original Toyota belt, and I believe this is the problem

As far as the AC compressor . . . if the clutch is bad, replace the whole AC compressor. Get a Denso with clutch installed. Denso is the original manufacturer, I believe.

You wouldn’t want to replace the clutch, only to have the compressor itself fail catastrophically a few weeks later, shooting metal debris into the system. If that were to happen, it’s going to get a little more expensive.

And while you’re at it, also replace the receiver-drier, since you’ll be “opening up the system”

Mine does same thing, it got wet from overheat condition, now it makes a wuuuring noise when clutch engages. If I turn the air off, no noise.

Maybe you could send us a sound clip…

Who, the person that started this thread or the person who revived it 3 years later.

I had a similar problem last year with my 99 Dodge Durango. The noise would not last while the A?C is on, but only for a few seconds after the clutch engages.

Come to find out my clutch was completely worn. Replaced it for about $35 and all has been well since.

Top row are the new clutch parts, bottom row the worn parts.

Holy crap…didn’t see the date of this thread

Yeah but the answer is the same regardless of the age of the question. I had the clutch replaced once when it was making noise. Still it wasn’t too long after that that the compressor went. So I don’t know, you hate to replace a compressor if you don’t have to. But mine was substantially more than $35.