Air Delivery Description and Operation: Recirculation
WARNING: This page is about a different car, the 2007 Cadillac DTS. However, it is still accessible from the selected car via links, so may be relevant.
The HVAC control module controls the air intake through the recirculation actuator. Recirculation is not available when the mode is in defrost or defog. When the mode is in floor, recirculation will only be available for 3 minutes. If the system is in full (100%) recirculation continuously for more than 20 minutes, the recirculation actuator moves to a 95% recirculation door position. The HVAC control module will prevent the system from returning to the full recirculation position until the next ignition cycle. In the outside air position, the incoming air is filtered by the passenger compartment air filter.