97 4runner 3.4 v6. 257K miles. It squeals when it's low rpm and the AC won't blow cold. Once the rpm's are up and above 1500, it quits squealing and the AC blows cold. I've tried screwing the tensioner bolt in and it didn't help. When I screwed the bolt out, it now spins constantly without stopping, but it does squeal, as you can see in the video.


Should I continue to screw it out more? What could be the problem? I've brought it out about a half inch. It's a little tight to turn the belt 90 degrees, just to give you an idea of the tension.

Thank you,

 

You should have between 1/4" to 1/2" of deflection in that belt.
It may be worn.
If you replace it do them all.