Well i get to troubleshoot yet another pesky vacuum problem. This time related to my a/c system. The defrost vent simply will not shut off. I have turned the system to max blower and min temp, and it still stays on the defrost vent. Sure, some air comes out the normal a/c vents, but not near as much as came out yesterday or earlier today. Also, the car wont shut off quite as quick anymore eiather, it kind of dies out instead of instantly shutting off like it used to. The brakes seem fine however, so my leak can't possibly be all that bad. Any ideas on where to start? the car is a 1983 300SD
thanks
Ryan