If you have narrowed it down, and it only occurs when the compressor is engaged, you are probably correct. Adding some oil is not necessarily a bad idea, as long as it is an ounce or so. My feeling is, it won't make a difference. If there is already noise, the damage is done, or in progress. It would be like adding oil to an engine that has a scored bearing. It is equipped with a variable displacement scroll type compressor, and there is a lot of moving parts within.
Thursday, October 14th, 2010 AT 9:33 PM