94 accord lx compressor

what causes the clutch to go bad? a couple of days ago i turned on the ac for the defroster, and smoke started to come out from the front end. at first my mechanic thought that it was the alternator, cuz it smelled burnt. after putting a new alternator in, i turned on the car and then the a/c and smoke started to come out from the compressor. also would this affect the alternator too? cuz the burnt smell was there also. the mechanic put back the old alternator.

i would lean more towards a frozen compressor and the belt was smoking