There is a rattling noise when I have my Outlander running with the AC on. If I completely shut off the ac the noise stops. Does anyone know what could be wrong? It's a 2008 Mitsubishi Outlander XLS V6.

 

Update took it into Firestone the first thing they thought it could be was the compressor was going bad. They said they would not know till they get it up on a lift. I get a call back from them(dodging a bullet) they say the noise is coming from a rusted rotting heat shield on the exhaust that was causing the metal rattling sound. They simply removed it and the rattling is gone