Air Door: Description and Operation
Fresh/Air Recirculation Door (V113) Operation
A/C Control Module (J301) on vehicles with manually regulated A/C system
• The Recirculation door motor (V113) does not have a potentiometer, therefore this motor is always actuated in one direction (fresh air or recirculated air mode). The direction of control motor rotation is reversed by switching the positive and negative on the outputs of A/C Control Module (J301). The A/C control module detects via the current strength, which flows via the control motor, that is has reached its end position.
• The recirculation door motor does not have a potentiometer, therefore a malfunction at the control motor or in its wire connection is not always detected by A/C control module (J301).
• Fresh/recirculating air button - F - is installed in A/C Control Module (J301) (A/C system controls).
• On vehicles with automatic climate control system, the recirculation door motor is actuated via the "basic setting" function. The function of the Recirculation Door Motor Position Sensor (G143) is monitored by the Climatronic control module (J255) control motor. Check using "Vehicle diagnosis, testing and information system" (VAS5051B) under "Guided Fault Finding".
• With the A/C system switched off, recirculating air mode may result in windows fogging up (moisture in air increases in passenger compartment and then condenses on windows, there is no air dehumidification by the cold A/C system evaporator).
• The "Air Recirculation Mode" function is erased automatically after approximately 20 minutes after switching ignition on again. If windows fog up after switching on ignition again, air recirculation mode is to be switched off manually.
• In the event the air distribution rotary switch - B - is located in the "air to front windshield" position - D - and recirculating air mode was switched on by pressing fresh/recirculating air mode button - F - in this position of the rotary switch, recirculating air mode is to be switched off by pressing fresh/recirculating air mode button - F - so that fogged windows are defogged as rapidly as possible. A/C control module switches e.g. automatically to fresh air mode after rotary switch is set to this position (and LED lamp in button - F - goes out).
• Check function of fresh/recirculating air button - F - and activation recirculation door motor => [ Recirculation Door Motor (V113), Checking Function ] Testing and Inspection.
• Recirculation door motor, checking function, refer to=> [ Recirculation Door Motor (V113), Checking Function ] Testing and Inspection.
• Electronics in A/C control module (J301) and of recirculation door motor, checking function, refer to=> [ A/C Control Module and Recirculation Door Motor, Checking Function ] A/C Control Module and Recirculation Door Motor, Checking Function.