hi. Have a 99 s10 blazer with the 4.3l. Original compressor went bad, so headed to the junkyard and found the same one out of a 97. The problem is that the compressor works fine but is making noise at the pulley. And the tensioner seems to be
moving more then before. I checked and the 97 calls for a 960k6 belt and my 99 has a 950 on it. Do i need to get the 960, and will that elimanate the pulley noise.

Thanks!

 

Is the pulley on the replacement compressor larger than the original? If not, you should not need a longer belt.

 

Yes, the pulley is almost an inch bigger than the original. Instead of a 950k6, which advance auto calls for, there is a 955 on it. Plus,
when i turn the compressor off, the noise stops. Maybe the clutch
is starting to go?

 

Definitely sounds like the clutch is going bad.