thanks alot guys, that should help. i can hear a hissing sound at all times in the interior of the vehicle, so it could be some sort of leak. and yes i meant the rear defogger
i have a 1974 new yorker brougham. it has 22,000 miles and is all original. everything works except my air. the rear air works but when i press the buttons on the auto temp control 2, nothing happens, no sound even. any help?