Mid (Upper)

When the driver selects the UPPER mode, the blower motor turns ON. The driver may manually adjust the blower speed by turning the tan speed knob.

The vacuum actuators move to the following positions:
^ The heater and A/C programmer supplies vacuum to the defrost-A/C valve.
^ The heater and A/C programmer supplies vacuum to one side of the heater-A/C bi-level valve.
^ The air-inlet valve vents in the outside air position.
^ The defrost-A/C valve vents in the A/C position.
^ The heater-A/C bi-level valve vents in the A/C position.

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

The heater and A/C programmer energizes the air mix actuators in order to perform the following functions:
1. Determine the proper air discharge temperatures
2. Position the air mix valves accordingly