UPPER

The defrost and A/C valve and the heater and A/C BI-LEVEL valve are in the A/C position when the following conditions are present:
^ Vacuum is supplied to the defrost and A/C valve vacuum actuator.
^ Vacuum is supplied to one side of the heater and A/C BI-LEVEL valve.
^ The air inlet valve is in the outside air position.

The blower pulls interior air into the system. The air is heated or cooled. The air is then forced through the instrument panel outlets.

The temperature control circuitry activates so that the temperature knob can adjust the discharge air temperature.