Screaching sound-- loose belt?

Last week my 2011 V6 began making a squealing sound occasionally. I had 113K miles on the original serpentine belt and after the mechanic and I drove around to identify the sound, which would come and go, and be generally louder when there was more drag on the engine (like the a/c compressor running). He said the serpentine belt is probably getting old and slipping, so it was replaced. It made the same sound again on the way home. But then the next morning the new serpentine belt broke, and I had it towed to a different shop for replacement. The shop manager told me the first shop had simply installed the belt incorrectly. But now with another brand new serpentine belt it's still making the same noise.

My dad's old OLD truck used to have slipping belts even when the belts were brand new so I grew up listening to slipping belts every time I got in the truck, and this is the exact same kind of sound, like rubber squeaking as it's dragged across something.

Is there another belt under there somewhere that needs to be changed? There's a timing chain, so I know that isn't it, but maybe another fan belt? Or could there be some other problem that gives a similar sound? Thanks!

 

I wonder if the spring in your idler pulley is weak.

 

Just one belt. I'd check the idler pulley as suggested by AZreb.

 

Mine does this too when it's wet outside. I plan to replace the belt soon and check the idler pulley. If the spring is bad it's not putting enough tension on the belt and it'll slip

 

Thanks. I will check that. But not at the same shop. Dear gawd that place is incompetent (not just an incorrectly installed belt, that was actually their 3rd mistake).