two broken belts

notice that I got a squealing sound after riding with my a/c on for about 20 minutes. Would turn it off and it would stop. On the interstate at about 80 mph and my a/c went out. Got to my exit and noticed that my power steering was out also. Reached my destination and called a mechanic friend of mine and he suggested looking under the hood and see if I lost a belt. Checked and sure enough, the power steering pump belt and the a/c compressor belt were gone.

These were two relatively new belts, less than 6 months old. Anybody have any idea as to what would cause them to break? They weren't cheapy belts.

ac clutch coulda locked, pulleys arent align, water pump locked, belts were too tight, the belts werent manufactured correctly, or theres something on the pulley thats sharp and nicked the belt each rotation

I would guess they were tensioned too tightly, it's pretty common for people to do so. Ask your mechanic friend to check how tight they are when you replace them