Cam anybody suggest how I could find out for sure wether my air recirculation works. When I use my AC in my 88 300E and I press the air recirculation button, the red light on the button comes on, but other than that I can not tell any difference. When there is something "smelly" outside such as a stingy exhaust from another car, it quickly gets in my car even with the air recirculation on. There are no leaks from anywhere else in the vehicle, door seals and such are all fine. Thanks for any help.