A/C Pulley Problem Options

[lazarpaul]

Two days ago my car started making this weird squeaky/winding noise from the drivebelt area of the engine. Today I took off the belt and I was checking the alternator, which I replaced just 2 weeks ago, and it was making a little bit of squeak when spinning the pulley. So I replaced that, as it had lifetime warranty but after that, the noise was still there. So I pulled that underbody protection plastic out and started listening to every sound in that area. It kinda sounds like it's coming from the A/C. Took the belt off and the A/C pulley has a little bit of play in it and you can here some crackling sounds when spinning it. The noise kinda changes a little bit when I turn the A/C on and it also becomes a lot louder if I rev up the engine.
So, what do you guys think? Is there any other way to test this. And if I need to replace it can I replace just the pulley or do I need to replace the whole compressor.
Thanks.