Recirculation Mode

When the recirculation switch is pressed, a ground is provided from the HVAC control module to the recirculation actuator through the recirculation door control circuits. The recirculation actuator moves into the recirculation mode. This brings air from inside the vehicle instead of air from the outside.

The HVAC control module provides power and ground to the recirculation actuator. The HVAC control module receives power from the rear fuse block through the ignition 3 voltage circuit. Ground is provided by the ground circuit.

The recirculation actuator is a reverse polarity motor. Each circuit provides both power and ground to the recirculation actuator. When the recirculation actuator is being held in position, both of the recirculation door control circuits have 12 volts applied to both sides of the actuator motor. This holds the actuator stationary. When RECIRCULATION is requested, one of the recirculation door control circuits will ground, driving the recirculation actuator into recirculation mode. When outside air is requested, by pressing the RECIRCULATION switch again, the other recirculation door control circuit will ground. This moves the recirculation actuator to draw in outside air.

The recirculation mode can be used in both automatic and manual operation. The only time recirculation is not available is when FRONT DEFROST is selected. The RECIRC LED will flash to alert the driver that recirculation mode is not available. Pressing the recirculation switch, from the OFF position, will set the blower, mode and A/C compressor clutch into automatic mode.

When in automatic mode, recirculation will stay on until either the vehicle operator selects outside air, by pressing the RECIRCULATION switch, or the HVAC control module automatically moves the recirculation actuator. Automatic recirculation is only available when air temperatures are 10°C (50°F) or warmer. There is a time limit when heater recirculation is selected. Recirculation will be allowed for 20 minutes when ambient air temperature is -1°C (30°F) or colder and engine coolant temperature is 60°C (140°F) or warmer.

The recirculation actuator will move automatically when coolant temperatures reach 117°C (243°F). This allows the refrigerant gases to cool and takes some of the load off the A/C compressor. When coolant temperatures reach 112°C (234°F), the HVAC control module will return the recirculation actuator to the previous setting.