I drive a 97 DX coupe, I have 79000 miles on it, and over the last few weeks I have had a rattling noise coming from under the dash. It only does it when the car is at a standstill. As soon as I add gas in gear it stops. i was thinking an AC compressor, but I don't know alot about mechanical stuff yet. The heater and AC can be on or off and it acts the same. Any ideas??