GF83.40-P-2102-01A Recirculated air button, function  

Function with automatic heater (HEAT) and air conditioning (Tempmatic)
When the recirculated air button ( ) is pressed the electro-magnetic fresh/recirculated air flap switchover valve is actuated for control of the recirculated air flap.
  Function with automatic air conditioning (automatic EC)
When the recirculated air button ( ) is pressed the electro-magnetic fresh/recirculated air flap switchover valve block is actuated for control of the recirculated air flap.