Car Air Conditioner Problems...?
the doors that control which ducts the air flows through, are controlled by vacuum motors, which are in turn controlled by the switch on the dash. most likely the motors have gone bad and are not holding vacuum. you can test them easily by taking a length of vacuum lineof the right size, attach it to the vacum motor, and suck on the open end. you should see the motor move. if you seal the vacuum in with your tongue, the motor should remain in place. if it passes these tests, then either the lines to the motors, or the switch is bad. if not then the motor is bad. there is also the possibility that both are bad, so keep that in mind.