Squeaking sound coming fromt belts when AC on

[Javila21]

so recently my 3 (2010 itouring) has been making this squeaking like sound when I first turn on the car it comes from the belts and only when then ac is turned on. if I turn off the AC then the sound goes away. also the sound goes away after the ac has been left on for a while & its barely cooling the car. im guessing a AC recharge is needed? if not what do you guys think it might be?, thanks in advance!

 

[concept]

It could be:
1. AC compressor bearing is starting to go, creating additional torsional resistance (unlikely).
2. The belt that is routed around the AC pulley needs to be tightened. (I'd try this, first.)

 

[Google]

what about an alternator going bad?

 

[Javila21]

so took the car to get its regular oil change at the mazda dealer. explained the sound I was hearing to the mechanic and everything else. car is 100% fine, he said water might of gotten inside the belts or something like that I don't recall. but the day was kind of cool it wasn't as hot and he did not hear the noise, so im guessing it only does that on hot days. other than that he said the car was perfectly fine.