Mode Selector Knob

Mode selector knob actuates a vacuum selector valve, which directs vacuum to open and close vacuum motor-controlled doors. With knob in NORM A/C, VENT, FLOOR, MIX or DEF (defrost) positions, outside air is drawn into system by the blower motor. With knob in OFF or MAX A/C position, the outside/recirculation door is positioned so outside air cannot pass into evaporator case. See Figure.