Recirculation Operation
WARNING: This page is about a different car, the 2002 Pontiac Grand Prix. However, it is still accessible from the selected car via links, so may be relevant.
Recirculation is only available in MAX. When MAX mode is selected, vacuum is applied to the recirculation actuator. The force of the vacuum overcomes the spring pressure of the spring inside the actuator. This moves the actuator, which is linked to the recirculation door, into recirculation mode. This brings air from inside the vehicle instead of fresh air from the outside.