dumbenhaue

I have a 2007 ES350. It started making a vibrating noise and sometimes screech coming from the serpentine belt area. It stops when I turn off the A/C and also stops when I accelerate with the A/C on (only does it when idling). Any ideas? Thanks.

NickTee

How about when you raise the RPM slightly from the 650ish RPM idle to say, 800RPM? If not, at what RPM does the screeching stop while you're sitting still? Does it remain or does it go away after a certain amount of time?

dumbenhaue

It stops almost as soon as I step on the gas but it starts again as soon as I let off the gas. Stops when I turn off the air conditioner.

Nelexus88

My first guess is the belt tensioner is bad which allows the belt to slip resulting in the noise you hear. Otherwise the AC compressor could be failing and starting to lock up under certain conditions causing the belt to slip.