Pontiac Repair: 2000 Sunfire 2.4 HVAC, vacuum tank, vacuum leak

Question
Hey Todd, I've been having some issues with my climate control on my 2000 Sunfire (2.4L) Ever since I bought the car used the vent selector switch has never worked properly. No matter what setting I have it at, air will come out top and bottom level. The only mode that works properly is defrost mode. I replaced the whole control assembly, but the problem persists. I've done some research and think it might be the MODE VALVE, or VACUUM TANK, or MODE ACTUATOR. Please shed some light on my problem and point me in the right direction. Thanks!

Answer
Hey Pete:

Your on the right track. You more than likely have a vacuum leak somewhere the default position for the doors is full air out the defogger. pull out the head and check to see if you indeed have vacuum on one of the hoses usually the supply vacuum is a purple hose if you don't have any vacuum on any of the hoses you have to trace it back out through the dash and into the engine compartment more than likely it's a dryrotted hose or end on the hose. I can't remeber how that vacuum hose is routed but look on the emission label under the hoos it shows the hoses and their routing. if you do have vacuum to the control head the next setp will be to check it at the mode actautaors on the hvac assembly. good luck :}