cleaning my a/c compressor

Hmmm... somewhere, I've seen a chrome, bolt-on shroud for the AC compressor. If it wasn't March then I can't recall who it was that made the thing.
 
He's not crazy, I have seen the covers as well.
To answer the original question:
Use wheel cleaner on it. The stuff kicks ass on bare aluminum. Be careful not to get it on the polished or plated or you will be re-polishing.