Voltage passes through FUSE 4 and CKT 41 to the heater - A/C control when the ignition switch is in the RUN position. The voltage from CKT 1199 and CKT 1236 varies from the battery to approximately 1.5V by the temperature control potentiometer. The control assembly provides ground paths for the vacuum/electric solenoid though CKT 150 and the control switches.
The air inlet valve closes the outside air inlet recirculating the air through the A/C system for maximum cooling. The outside air inlet closes when the vacuum is applied to the actuator. The air inlet valve actuator is vented. The spring returns the recirculation valve to position A and allows outside air to be drawn into the vehicle.
The air temperature valve determines the amount of air flow through the heater core. The heater core which determines the air temperature of the outlets. The electric actuator moves the air temperature valve. The voltage level of the temperature control output from the heater - A/C control determines the position of the Air Temperature Valve. The ignition switch in the RUN position powers the electric actuator. The FUSE 4 and CKT 41 applies the voltage.
The outer mode valve determines the airflow direction to the I/P outlets or the heater/defrost outlets. Without the vacuum applied to the actuator, the valve is in position A directs the air to the heater/defrost outlet.
The small inner and outer mode valve allow the partial airflow to the I/P outlets when the outer mode valve is in position A. The vacuum applied to the inner and outer mode valve actuator opens the inner and outer mode valve.
The defroster valve assumes three positions. The defroster valve is operated by a bi-directional vacuum actuator which moves the valve in two positions. The valve is in midposition and no vacuum is applied to either actuator. The Airflow valve in midposition B is delivered to the defrost outlets at the windshield and the heater outlets at the floor level. When the heater solenoid is activated, the following conditions occur:
- The red vacuum hose supplies the vacuum applied to the defroster valve actuator.
- The actuator moves the valve to position C, forcing all airflow to the heater outlets.
The defrost solenoid activates under the following conditions:
- The blue vacuum hose supplies the vacuum applied to the defroster valve actuator.
- The actuator moves the valve to position A, forcing all air to the defrost outlets.
