Recirculation Mode

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

When the recirculation switch is pressed, the HVAC control module will apply a ground to one of the recirculation door control circuits in order to obtain the desired position. The recirculation actuator is a reverse polarity motor, each circuit provides both power and ground to the recirculation actuator. When the actuator is being held in a stationary 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 a recirculate position is requested, one of the recirculation door control circuits will ground driving the recirculation actuator into the desired position. When an outside air position is requested, the other recirculation door control circuit will ground. This moves the recirculation actuator into an outside air position. This brings air from outside the vehicle instead of air from the inside.

The HVAC control module provides power and ground to the recirculation actuator. The HVAC control module receives power from the under hood electrical center through the ignition 3 voltage circuit. Ground is provided by the ground circuit.

The recirculation mode can be used in both automatic and manual operation. The only time recirculation is not available is when FRONT DEFROST and mix blend mode 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 21°C (70°F) or warmer. The recirculation actuator position will vary to obtain a cooler duct air temperature when cool air is selected. This will assist in cooling the vehicle quicker.

The HVAC control module will move the recirculation actuator to the outside air position at ignition off to bring fresh air to replace stale air that has accumulated in the HVAC module during shut down.

When requested the recirculation actuator will be able to move to the 100 percent recirculation position for a limited time, after that limited time the actuator will move to the 90 percent position. In the auto mode only, the recirculation actuator will move faster to the recirculation position when vehicle is at an idle compared to the normal speed of the actuator during normal operation.

If the recirculation actuator or related circuits has a failure the HVAC control module will attempt to drive the actuator to the outside air position regardless of mode selection. If there is a failure with one of the air temperature actuators the HVAC control module will allow the recirculation actuator to move to the outside air position.