You mentioned that engine need not be started for the noise to occur so I don't think it has anything to do with the receiver drier.
Did you check the condenser fan motor to see if it is working when ignition is turned ON?
At the right side of engine compartment there are not many things that can emt buzzing noises. I would suspect a relay that is more probable.
Friday, November 6th, 2009 AT 6:50 AM