Under the dash on the passengers' side, the vacuum lines run into a connection which has many vacuum lines (multi-colored, they kinda resemble wires). These vacuum lines activate vacuum actuators which will switch the air from defrost to floor and then to vents as you move the selector.
If all of the lines are getting vacuum when you select either floor, defrost or vent, then the suspect part is the switch itself.
Monday, April 29th, 2013 AT 7:47 PM