Belt Squeeling like a Mofo

[gumby002]

Hello
My belt squeals.
Here is what my observations are:
-Replaced Water pump & belt a few years ago
-Replaced Alternator 2 months ago
- Belt squeals when AC is on - I live in FL...AC button is always on
- With the hood up, I can see that the belt, when squealing, is not moving.
- Belt does not squeal when the AC light is off most of the time. If it does, its for 2-3 seconds only.
- AC does blow cold air, really cold, but it takes a minute or so of the squealing and then not squealing for the air to get cold

I am thinking that its the AC unit that is causing this. Its an uneducated guess because I've replaced 2 of the 4 pulleys/sheaves already.

Thoughts? Things I should try? Am i on the right track?
Thanks!
James

[WeeYari]

Simple question first since it is not listed above. Have you replaced the belt? Could be getting extremely glazed if you have not.

[gumby002]

yeah, forgot to add that. The belt was replaced when the water pump was replaced
And I've sprayed the belt with belt dressing when the squealing really got bad thinking that maybe the belt wasnt gripping the new alternator sheave.

[bronsin]

I would loosen the belt so I could turn the pulleys by hand. Perhaps one of them isn't freely turning?

Good luck!

[dogsridewith]

simpler question--did you check and/or raise belt tension?

[MUSKOKA800]

I had good luck with Gates belts when running my previous Yaris with the Blitz S/C.
My current stock Yaris needed a belt and I put on a Continental belt. It seems to stretch constantly. Every month it will start squealing at start up with the AC on. Switch of the a/c and it stops and fine later once warmed. I need to tighten it monthly to resolve this issue. Reference marks I put on the alternator arm each time show that it's the belt growing, not slipping adjustment. No more Continental belts in the future for this guy!

[dogsridewith]

Belt on new-to-me 2007 seemed so tight I match-marked the setting and loosened it some. Still no squeal.
MUSKOKA800's keeping it at incipient squeal will be best for various accessory bearings...one of those owner-mechanic advantages, where the shop has to overtighten to deal with the stretch.

[MUSKOKA800]

Yes, I just keep adjusting it about 1/8th inch at a time. Just enough to silence it. Certainly don't want to trash the alternator or water pump bearings due to extreme belt tension.