RECIRC
The air inlet valve moves to the recirculation position when the vacuum is supplied to the following components:^ The air inlet vacuum actuator
^ The defrost and A/C valve
^ One side of the heater and A/C BI-LEVEL valve vacuum actuator
The blower pulls interior air into the system. The air is heater 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.