I own a 2000 Dodge Dakota Quadcab (94000 miles). I have a ventilation door problem. Any selection on the air circulaion control that should utilize the upper vent outlets causes the air to blow from the heater outlet. Sometimes, on the low blower setting, air will come out of the upper vent outlets until a higher blower setting is used, then it reverts back to the problem described above. Any ideas? Thanks.
You have a vacuum leak before it get to the controller. Go under the hood and find a black round vacuum canister with two lines connecting. Trace the one to the engine and see if it is broken. They are plastic and often burn and crack causing a loss of vacuum.