I have recently acquired a 92 full-size Chevy blazer with a 350. At first everything was OK. Then summer came and I started to try and use the AC more. Sometimes with the AC on it would slip the belt off. After ruining one compressor because the belt sheared off the wire plug, I picked up another compressor.

After installing I noticed the crank pulley seemed out of balance and it would pop the belt off of the idler pulley. I eBayed another pulley. Installed it. Same problem. Did some forum searching. Found the harmonic balancer to be the usual cause of this. Just installed a new harmonic balancer today. Still exactly the same. Nothing improved. My only thoughts now are the crank shaft is bent or my new harmonic balancer is bad. Anyone else seen this issue? Its hot in Vegas. I need the AC.... help. Thanks for any input

 

Don't have too much experience with the harmonic balancer, although my crank pulley seems to be wobbling a bit and I am getting a knocking sound in coorelation with my serpentine belt travel so I may become real experienced with it soon. I will say that it almost sounds like a belt issue. You might want to double check the size. Did the problem present after replacing the belt with a new one? I know that my Blazer must run an GOODYEAR Gator Back belt or it sounds really loud against the pulleys. Also check to make sure your tensioner pulley, and all pulleys for that matter, are turning smoothly and that the bearings aren't going on any of them. I would think that you would know by other symptoms if your crank shaft was bent. Hope this helps.