http://www.youtube.com/watch?v=HFY8YR3SZ-o

When the heat or a/c is turned on the noise goes away as you see in the video. Once the fan is turned off the noise comes back.

It's really loud and annoying but what is it?

bumpp

LOL that is definately your AC compressor you need o get it changed. If its not too hot where you are located and you can't afford a compressor right now and u don't use the ac that much u can just remove the belt so that you won't have to hear that annoying noise.

Jerry

Hey thanks for the reply. My friend actually picked up a spare compressor from a junkyard a few months ago but we weren't sure if that was the problem so we didn't bother changing it out because it looks like a PITA LOL.