Today my friend and I installed a new alternator belt, since the last broke on his '99 Integra GS-R. Well now that we have everything installed and the car running, we tried out his a/c and to our surprise we found a huge annoying pig squealing sound coming on everytime we turned on the a/c. Anyone know why this happens and how can we diagnose this problem?

 

The belt is slipping or you put the wrong kind of belt on.

 

My friend had this problem with his 94 integra, turns out that he was in need of a new radiator

 

I had that same problem. I sprayed a generous amount of belt dressing on the belt (contact side) and the squeal went away. The best way to spray the belt is from under the engine.

 

why don't you replace the AC belt as well?

 

The spray isnt really good for the belt, as it takes away some of its physical characteristics. Sure the squeak will go away, but the belt will need replacement soooner.

Just retension the belt or replace it if its chewed.