HTR/Defrost

The Heater/Defrost Valve can assume three positions and is operated by a bi-directional vacuum actuator which can move the door to either of two positions. If no vacuum is applied to either vacuum actuator, the valve is in midposition. Air flow with the valve in midposition will be delivered to the defrost outlets at the windshield, heater outlets at floor level and window defrost outlets. When the HTR Vacuum Actuator (red vacuum hose) is operated, the valve is positioned to direct air flow to the heater outlets and slight air flow to the defrost outlets. When the DEFR Vacuum Actuator (yellow vacuum hose) is operated, the valve is positioned to direct air flow to the defrost outlets and slight air flow to the floor outlets.