Function Selector Switch
Function selector switch combines a vacuum selector valve with 2 electrical switches to supply power to clutch circuit and blower motor control circuit. Function selector knob can be placed in MAX A/C, A/C, PANEL, OFF, PANEL & FLOOR, FLOOR, FLR & DEF (floor and defrost) and DEF (defrost) positions. MAX A/C and A/C positions control compressor operation. PANEL, PANEL & FLOOR, FLOOR, FLR & DEF (floor and defrost) and DEF (defrost) positions direct airflow to chosen outlets. Defrost position activates compressor to dehumidify air directed at windshield. Function selector knob position determines which mode doors are open, partially open or closed. Mode doors direct airflow to selected outlets. See VACUUM DIAGRAMS .
When function selector knob is in maximum A/C position, air inlet blend door is at full vacuum, closing off outside air and allowing only recirculated air. See Fig 1. Defrost blend door is at full vacuum while footwell blend door is at no vacuum, closing both doors. Vent/register blend door is at partial vacuum, directing airflow to driver side, passenger side and center registers. Temperature control is usually set for maximum cold but may be heated if selected. Air is picked up at recirculation opening by blower motor. With temperature control set for maximum cold, air flows across evaporator core, diverting past heater core and then directed into passenger compartment through driver side, passenger side and center registers. Compressor is enabled when MAX A/C is selected. Blower motor is on.
When function selector knob is in A/C position, air inlet blend door is set at no vacuum, blocking recirculation passage and admitting outside air. See Fig 2. All other door positions are same as described under MAX A/C. Temperature setting can be changed manually. Compressor is enabled when A/C is selected. Blower motor is on.
When function selector knob is in panel position, air inlet blend door, with no vacuum being applied, blocks recirculated air and allows outside air. See Fig 3. Air flows through system to driver, passenger and center registers. Vent/register blend door is at partial vacuum to direct airflow to driver, passenger and center registers. Defrost blend is at full vacuum and defrost airflow door is at no vacuum, closing off airflow to windshield defroster hose nozzles and footwell ducts. Temperature setting can be changed manually to heat air but air cannot be cooled below outside temperature. Compressor is disabled when VENT is selected. Blower motor is on.
When function selector knob is in off position, air inlet blend door is at full vacuum, closing off outside air and allowing only recirculated air. See Fig 4. Vent/register blend door is at no vacuum and defrost, footwell and blend airflow doors are at no vacuum, closing off passages to driver, passenger and center registers. Blower motor and compressor are off.
When function selector knob is in panel/floor position, air inlet blend door is set at no vacuum, blocking recirculation passage and allowing outside air. See Fig 5. Footwell blend door is in full vacuum position, and panel airflow door is in full vacuum position allowing airflow to blend between panel vents and footwell ducts. Defrost airflow door is at full vacuum, closing off airflow to windshield defroster hose nozzle and directing airflow to heater outlet footwell duct. Compressor is enabled when PANEL/FLOOR is selected. Blower motor is on.
When function selector knob is in floor position, air inlet blend door is in no vacuum position, blocking recirculation air and allowing outside air. See Fig 6. Footwell airflow door is at full vacuum position, opening door and allowing airflow through footwell ducts. Defrost airflow door and vent/register blend door are in no vacuum position, closing off airflow to windshield defroster hose nozzles and driver, passenger and center registers. Temperature control can be positioned to mix air flowing through and around heater core to achieve selected temperature level. Compressor is disabled when FLOOR is selected. Blower motor is on.
When function selector knob is in floor/defrost position, air inlet blend door is in no vacuum position blocking recirculation air and allowing outside air. See Fig 7. Footwell blend door is at full vacuum allowing air to flow through footwell ducts. Defrost blend door is in no vacuum position, allowing airflow to both windshield defroster hose nozzle and side window demister hose nozzle ducts. Vent/register blend door is in no vacuum position. Compressor is enabled when FLOOR/DEFROST is selected to dehumidify air and reduce windshield fogging. Blower motor is on.
When function selector knob is in defrost position, air inlet blend door is in no vacuum position, allowing outside air. See Fig 8. Defrost blend door is at no vacuum, directing airflow to windshield through defroster ducts and side windows through demister ducts. Panel airflow door and footwell airflow door are in no vacuum position so that most of incoming air is directed to windshield defroster hose nozzle. There is also airflow to side window demister and hose. Temperature control knob setting will determine amount of air that is directed through heater core and amount that bypasses heater core. Compressor is enabled when DEFROST is selected to dehumidify air and reduce windshield fogging. Blower motor is on.