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Ventilation system, function - GF83.10-P-2000CE

MODEL 204.0 /2 as of model year 2009 /YoM 08 

MODEL 204.3 

MODEL 204.9 

Air outlets in passenger compartment (Shown on model 204.0 with code (581) Comfort automatic air conditioning) 

Fig 1: Identifying Ventilation System Operation Diagram (Air Outlet In Passenger Compartment)
G07532066Courtesy of MERCEDES-BENZ USA

Function requirements general 

IMPORTANT The electronic ignition lock control unit (N73) transmits the status of circuit 15 via interior CAN (CAN B).

Ventilation general 

The ventilation system prevents windows from fogging up, supplies air to the vehicle occupants, and ensures that uniform and pleasant temperatures in the vehicle interior are reached quickly. When the fresh air/recirculated air flap is adjusted correspondingly, fresh air is supplied to the air conditioner housing via the air inlet. Depending on the current settings on the AAC [KLA] control and operating unit (N22/7), the air is routed into the vehicle interior through air ducts and air outlets.

IMPORTANT In order to prevent fogging of the windows, after t = 2 min after switching off circuit 15 the defroster flaps and the fresh air/recirculated air flap are closed and the footwell flaps are fully opened. After starting the engine, the defroster flaps and the footwell flaps remain in this fixed position for t = 30 s. The fresh air/recirculated air flap can be adjusted immediately. After that, all adjustments are possible again.

IMPORTANT With "Circuit 15 Off" the fresh air/recirculated air flap is opened 50% by the fresh air/recirculated air flap actuator motor (M2/5) and the ram air flap (with code (581) Comfort automatic air conditioning) by the ram air flap actuator motor (M2/34) (up to 31.5.10) or by the fresh air/recirculated air flap actuator motor (as of 1.6.10) when one of the doors is opened. This achieves a significant reduction in the door closing forces. The function can be set with the diagnostic tester.

The ventilation system comprises the following subfunctions:

AC component actuation function sequence 

The AC component actuation function sequence comprises the following subfunctions:

Function sequence, actuation of blower motor 

Ventilation is achieved with the aid of the blower motor. The AAC [KLA] control and operating unit forwards the request straight to the blower regulator (A32n1), which then actuates the blower motor.

With code (581) Comfort automatic air conditioning, the ventilation of the rear passenger compartment is also supported by the rear blower motor (M2/1).

Actuation is performed by the control and operating unit over the climate control LIN (LIN B8).

IMPORTANT With an active voice control system (VCS [SBS]), the blower output is limited. For this purpose, the radio with auto pilot system (A2/56) (with code (511) Audio 50 APS with DVD changer) or COMAND controller unit (A40/3) (with code (512) COMAND APS with DVD changer or with code (527) COMAND APS with single DVD drive (with navigation)) transmits the status of the VCS [SBS] to the control and operating unit via the interior CAN. This then limits the blower output.

IMPORTANT In vehicles with code (B03) ECO start/stop function, the blower output is limited when the engine stops.

The CDI control unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit (N3/10) (with gasoline engine) transmits the signal "Engine stop release" via chassis CAN (CAN E) to the front SAM control unit with fuse and relay module (N10/1). This sends the signal over the interior CAN to the control and operating unit. The control and operating unit then limits the blower output.

Air ducting flaps actuation function sequence 

The air distribution in the vehicle interior is controlled by corresponding adjustment of the air duct flaps in the air conditioning housing. The control and operating unit actuates the following components over the climate control LIN: Vehicles without code (581) Comfort automatic air conditioning:

Fresh air mode function sequence 

The fresh air/recirculated air flap is opened and fresh air is delivered into the interior by means of the air conditioner housing.

Air recirculation mode function sequence 

The air recirculation mode function sequence comprises the following subfunctions:

Function sequence for air recirculation mode using air recirculation mode button 

When the air recirculation mode button on the control and operating unit is pressed for t < 1.5 s, the fresh air/recirculated air flap is closed, and thus the supply of outside air is prevented. The air only circulates in the vehicle interior and unpleasant odors and harmful gases are kept out. The light-emitting diode (LED) in the air recirculation mode button lights up.

Pressing the air recirculation mode button for t > 1.5 s activates comfort air recirculation closing.

The windows and the tilting/sliding roof (with code (414) Electric glass tilting/sliding roof) or the panoramic sliding sunroof (with code (413) Panoramic glass sunroof with top sliding sunroof) are then automatically closed.

When the air recirculation mode button is pressed again for t > 1.5 s, the windows and the tilting/sliding roof or the panoramic sliding sunroof return to their previous positions.

IMPORTANT The windows, tilting/sliding roof or the panoramic sliding sunroof, which were manually opened during the air recirculation phase, are not moved back to their previous positions once the air recirculation phase is over.

IMPORTANT On vehicles with code (460) Canada version and code (494) USA version, comfort recirculation closing is not possible.

IMPORTANT The detailed convenience recirculation closing procedure is described in the convenience feature (CF [KFB]) function.

Additional function requirements for pollutant-controlled air recirculation mode (with code (581) Comfort automatic air conditioning) 

Function sequence for pollutant-controlled air recirculation mode (with code (581) Comfort automatic air conditioning) 

The pollutant sensor (B31) sends the pollutant values for the outside air over the climate control LIN to the control and operating unit. Starting from a certain pollutant concentration, the fresh air/recirculated air flap is automatically set to the recirculated air position.

Outside air supply is prevented and only the inside air is recirculated. If the conditions for pollutant-controlled air recirculation mode exist after the engine is started, a supply of fresh air is first provided for t = 30 s.

Following this, the pollutant-controlled air recirculation mode is initially implemented with a degree of efficiency of 80 % and after an additional 10 s completely (100 %) if still required. The pollutant-controlled air recirculation mode is not displayed via the LED.

Function sequence for ram air operation 

Ram air operation is speed-dependent. The speed signal is sent by the instrument cluster (A1) to the control and operating unit over the interior CAN. The following 2 versions can be differentiated in ram air mode:

Vehicles without code (581) Comfort automatic air conditioning 

In a vehicle speed range between v = 60 km/h and v = 160 km/h the fresh air/recirculated air flap is gradually closed by the fresh air/recirculated air flap actuator motor. As of a speed of v > 160 km/h, the fresh air/recirculated air flap is closed completely.

Vehicles with code (581) Comfort automatic air conditioning 

In a vehicle speed range between v = 60 km/h and v = 160 km/h, the ram air flap is closed in stages by the ram air flap actuator motor (up to 31.5.10) or by the fresh air/recirculated air flap actuator motor (as of 1.6.10). As of a speed of v > 160 km/h, the ram air flap is closed completely.

REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic for automatic air conditioning, input signals PE83.40-P-2052-97FAB
REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic for automatic air conditioning, actuation PE83.40-P-2053-97FAB
  Overview of automatic climate control system components GF83.40-P-9995CE
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