Engine Noise ONLY when AC is on

[hbaldana]

Hello all...

My 99' E46 is making a rattling noise when the AC is on.. ONLY when the AC is on. It sounds as if the engine fan is hiting something... but it is not. I have read many threads related to AC issues but have not found one with the same problem. The noise comes from the front of the engine (left side if you are standing infront of it) but I can not tell where exactly is coming from.

Could it be that it needs to be re-charged?
Should I evacuate and re-charge?
How do I get the air out and then re-charge?

Someone said that if there is air in the system it will make the rattling noise.

Can I just use the "Walmart" recharge kit and do it myself??

Please advice.