No matter where you put the control knob the a/c will blow out of the a/c vents but mostly out of the heater vent on the floor. Defrost will not work at all. Is this a door problem or is it the door actuator. The control switch will shut everything off when you put it in the off position. How can I check the switch.
It is hard to remember if they used electric or vacuum to actuate the vent doors back then. However, I believe it was vacuum. Check to see if there are any vacuum leaks. If you have a vacuum gauge, check intake vacuum to make sure it is around 17+ lbs.