I turned mine on yesterday for the first time and it is quite a noisy system. The higher the rpm's the noisier it gets. (sounds like a bad wheel bearing vibration) Is this normal?
Im thinking the a/c pump is the question...or perhaps the belt is the problem.
Also, there is a 2 or 3 second delay when turning it on or off...not sure if that has anything to do with it.

 

All totally normal. The a/c unit on the cooper is very noisy, almost sounds like something is wrong. I assume it has to do with it being a smaller motor and the strain just being a little more than average. It definitely effects my off the line torque and acceleration throughout the rev band. I personally HATE my a/c on my MCS but my girlfriend can't live without it.

 

I guess im just used to my previous Honda's and was accustomed to my Accord's a/c...aw well, gotta make some sacrifices.
Im usually a window guy, but with the past couple days being in the mid 30's (celsius) and 100%! humidity...a/c was the answer

 

The a/c will often drone when it's working hard. Perfectly normal.