Video: Drive Belt Squeal Diagnosis
 

Hey jeepers

I recently changed my serpentine/drive belt in hope of solving the A/C squeal on a cold start. I replaced the old one with a gatorback belt.

My problem only occurs on a cold start when I turn the a/c on. The higher the RPM's at start (revving) the more it squeals. Also it seems to happen only at higher speeds of the fan. So if i start it in speed 1 no squeal happens. I ramp it up to 4 and it starts to chirp. It goes away after it gets a bit warmer. Take a look at the video I just took.

You can see the belt start to slow down and make the squeals once I turn the fan speed up to 4. Even more once I rev the engine a bit. Goes away once I turn the a/c off.

What could this be? Is this the idler pulley (doubt it, but hope so since it's cheap) or the a/c clutch? The old belt was pretty loose and squealed the whole time like I when I rev it now until it warmed up.

I had the same exact squeak and it ended up being my alternator. Not saying you have the same problem as I did but who knows. Good luck either way!

How did you figure out it was your alternator?

On my 85 2.5L I had a bad squeal and the tighter I got the belt the more it would squeal, chirp and squeek. Finally got it really tight and it started throwing belts. I finally got to looking at it and noticed the alternator wasn't aligned with the rest of the pulleys. Seems the bolt that held the alt in place was in the wrong hole and the more I tightened the belt the more it would torque the alt sideways. Put the bolt in the correct hole and got the belt just tight enough and it has been quiet ever since. Not sure on the routing of the newer engines, but be sure something hasn't pulled one of the pulleys out of alignment.

I'll do a visual inspection. I don't want to take out all the stuff to get back in there. At least it'll be easier the second time around..

Because my alternator eventually died a few months after the noise started, so I replaced the alternator and boom no more squeak!

While it's running, see if you can see any wobbling in any pulley. Also, take the belt off, and go through the pulleys and see if there's any play. Spin them around if possible and pray you hear one that doesn't sound good.

I was hoping you weren't going to say that

Just now watching the video, almost certainly the clutch. Take the belt off and feel the bearing and see if it feels gritty or has play.

Why do you say it's certainly the clutch? It's almost impossible for us to diagnose a squeal from a video. It could be any of the bearings driven on the belt. OP is just gonna have to take off the belt like you said and feel/hear all of the bearings.

Oh and OP, even though mine ended up being my alternator I could control the squeak with the AC controls as well. If I had my air turned off if rarely would squeak. Just because it squeaks with air on doesn't mean it's the AC clutch.(it could be the AC clutch just as easily though)

I had a similar squeal and it was the power steering pump being misaligned.

Because somewhere around 80% of the cars I've worked on and watched my dad work on growing up that had a squeal when the AC came on was because of the clutch. Just going from experience. And I said almost certainly, not certainly. But yes, they do need to take the belt off and find out for themselves which bearing it is. Hopefully I'm wrong and it's just a bad idler pulley or something super easy.

Another trick my dad taught me is to take some like half inch rubber line or something similar, put it up to my ear, and point it at each bearing, as close as I could. I believe the same thing can be done with a screw driver, but the screw driver has to be touching and on a moving part, it's not feasible. That's why the screwdriver method is saved for stuff like an engine knock or the like.

I believe there's also a water test. I'm not sure, but I think you spray water on the pulleys and if the squeal goes away, it's a misaligned pulley, and if it stays, it's a bad bearing. Again, not sure, but might be worth looking into.

Leave your A/C off and turn on headlights and rear defrost and any other electrical items. If it starts to squeal as you add load to the alternator, then you have your answer.