OK, don't call my stupid :screwy: I'm a newbie. My vent and a/c run fine. My system is charged. But on warm days and when I pull behind some nasty oil-burner, everything seems to come straight in as if I'm still pulling outside air like running the vent.

Before you reply, tell me everything. I have no clue what is where on this thing because I never have had to work on it before. :disappoin

Unless you are running the A/C on MAX you are drawing outside air.