Belts on a 98 GSX

Hi

I own a 98 GSX, it has clocked 85000 miles, and is in very good condition, few days back, screeching noise started from the engine, and suddenly one of belts broke, it was the alternator/hydraulic steering/water pump belt, which broke, I got it fixed by a local mechanic. After the repair the steering/water pump started to functio, but noise did not stop, when I took it back to the mechanic, he adjusted the belt tensioner, and said maybe the AC belt needs replacement.

At present, (when engine is cold especially), there is al loud screeching noise, and which completly subsides when the engine reaches 40-45mph mark. The noise is more when the AC is switched on immediately when the engine is started. Due to this reason I am switching the AC unit on once the engine has reached 40mph. All the belts look good to me, in fact except the one replaced all others are the original ones that came with the car. What coudl be the problem? Was the repair done in the right way or should I take to a authorized dealer to set it right?

Thanks a ton!