The old belt was worn when I changed it.
I compared the grooves with a coin check and it was a significant difference.
high pressure isn't released by a 'blow off' since r-12. has an electric sensor that just cuts off the clutch. the stethoscope is a good idea. i just used a long extension. idler pulley the most common culprit.
btw, all a/c compressor seals leak a tiny bit. it lubes the seal.
A metal rod and an empty soup can make a pretty good substitute for a stethoscope..
Guess the electromagnetic clutch won't really "stick"...