Function Control (Main)
The function selector switch can be placed in OFF, vent, floor, mix and defrost positions. Position of function selector switch determines whether function doors are open, partially open or closed. Function doors direct air flow to selected outlets. 3 vacuum motors and doors are outside/recirculated air, defrost/panel and defrost/floor. See VACUUM DIAGRAMS .
When VENT is selected, recirculation air duct door, with no vacuum being applied, will block recirculated air and admit outside air. See Fig 1. From there, air flows through system to instrument panel registers. Floor/panel door is in full vacuum position to block air flow to heater outlet floor duct. Floor/defrost door is at full vacuum, closing off air flow to windshield defroster hose nozzle. There is also some air flow to side window demisters. Temperature can be adjusted to heat air but air cannot be cooled below outside temperature. Blower motor is on.
When OFF is selected, recirculation air duct door is at full vacuum, closing off outside air and admitting only recirculated air. See Fig 2. Floor/panel door is in no vacuum position, closing passage to instrument panel registers. Floor/defrost door is at full vacuum, closing passages to windshield defroster hose nozzle. Blower motor is off.
When FLOOR is selected, recirculation air duct door is in no vacuum position, blocking recirculated air and admitting outside air. See Fig 3. Floor/panel door is in no vacuum position, blocking air circulation to instrument panel registers. Floor/defrost door is in full vacuum position, directing all air flow to heater outlet floor duct. Temperature can be adjusted to mix air flowing through and around heater core to achieve desired temperature level. Blower motor is on.
When MIX is selected, recirculation air duct door is in no vacuum position blocking recirculated air and admitting outside air. See Fig 4. Floor/panel door is in no vacuum position, blocking air circulation to instrument panel registers. Floor/defrost door is in partial vacuum position, allowing air flow to both windshield defroster hose nozzle and heater outlet floor duct. There is also some air flow to side window demisters. Blower motor is on.
When DEFROST is selected, recirculation air duct door is in no vacuum position, admitting outside air. See Fig 5. Both floor/defrost door and floor/panel door are in no vacuum position so that most of incoming air is directed to windshield defroster hose nozzle. There is also air flow to side window demisters. Temperature setting will determine amount of air that is directed through heater core and amount that bypasses heater core. Blower motor is on.