Latley since I've been using my a/c a lot, my car has developed this loud humm when i turn the a/c on. I'm talkin loud, like I've had people tell me something was wrong at lights in the last few weeks. It not consistent with my rpm's either, but if I'm idling the noise goes down. Anyone have any clues?

 

one time that happened to me and i had a piece of paper stuck in the a/c register on the floorboard of my prelude. just a thought..

 

Inside or outside the car? If it's inside, pull the blower motor assembly down. You've probably got some debris stuck in it. You may want to put a pair of gloves on though. Mice like to make their homes inside of those things. It really sucks pulling one down and seeing a dead mouse with a broken back fall out. If it's outside, more than likely the compressor is about to take a shit on you.