At times, there is a whirring noise that sounds like it is coming from the A/C. The noise fluctuates with the engine (higher throttle, more noise and less throttle, less noise). If I turn the A/C off, it stops. Any idea?

 

could be a compressor pulley. they commonly make noise and ive replaced a bunch of AC compressor pulleys for that. also the upper idler pulley whines too but will normally always make the noise regardless of the AC on or not.

 

wat is it W210 OR W211?????

 

How do I know W210 or W211? It is a 2004 E500.

 

210s didnt have a 500s they had 430s so yours is a 211chassis