GF83.20-P-2104-02E Fresh/recirculated air flap, function  

Function
When the pushbutton control module is switched to the recirculated air mode ( comes on), the vacuum element for the fresh air/recirculated air flap closes the fresh air opening and simultaneously opens the recirculated air opening. The blower sucks air out of the vehicle passenger compartment into the heater/A/C housing.

Function with HEAT (with dust filter)
When the button ( ) is pressed the system operates with
100 % recirculated air for approx. 5 min. The system switches
back to fresh air before expiration of the 5 min. when the button ( ) is pressed again or when the blower or ignition is switched off.
  Function with Tempmatic A/C and automatic A/C
Manual recirculated air mode
When the button ( ) is pressed the system switches over to 100 % recirculated air at outdoor temperatures of
> 15 °C for 20 min. and
< 15 °C for 5 min.

Automatic recirculated air mode
The system switches to 80 % or 100 % recirculated air depending on the refrigeration requirement at high outdoor temperatures.