I discovered another problem with my A/C system. When I first start the car up, the fresh air coming into the car has a very bad smell. If I shut the fresh air off and go to recirculate, the smell goes away and all is fine. Today, I pulled the cabin air filter out (just changed it 2 monthes ago) and it was clean and had no smell. I pulled the driver's side plastic cover off as that's where the air comes in and it was clean with no smell. Rubber seal for hood is in great shape. Their are no exhaust or oil leaks. Not sure where smell is coming from? 2006 LTZ with a 3.9.