Use a stethoscope to listen to the compressor while the engine is running and it's engaged. Also listen to the the radiator fan. Yours may have a separate AC condenser fan that is noisy. They typically only turn on when the compressor cycles on.
If the source of the noise is not obvious, there is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.
Thursday, May 2nd, 2013 AT 4:11 PM