Within the heater vent module is the inlet air door (1), the temperature actuator door (2), and the mode actuator door (3). These air doors are hinged parts that direct the airflow through the various sections of the heater vent module in order to provide the proper airflow for the selected operating mode.

Each air door is controlled by an actuator either the mode actuator (1), the inlet air actuator (4) or the temperature actuator valve (5).