Ventilation System, Function
GF83.10-P-2000RI Ventilation System, Function
Air outlets in passenger compartment
General function requirements
^ Circuit 15
General ventilation system
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/air recirculation 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), the air is directed into the vehicle interior through air ducts and air outlets.
In order to prevent window fogging, the defroster vent flaps and the fresh air/air recirculation flap are closed and the footwell flaps fully opened after t = 2 min after circuit 15 is switched off.After starting the engine, the defroster vent flaps and the footwell flaps remain in this fixed position for t = 30 s. After that, all adjustments are possible again. The fresh air/air recirculation flap can be adjusted immediately.
The ventilation system comprises the following subfunctions:
^ AC component actuation function sequence
^ Fresh air mode function sequence
^ Air recirculation mode function sequence
AC component actuation function sequence
The AC component actuation function sequence comprises the following subfunctions:
^ Function sequence, actuation of blower motor (A32m1)
^ Function sequence, actuation of the air ducting flaps
Function sequence, actuation of blower motor
Ventilation is provided with the aid of the blower motor. The control and operating unit transmits an actuation of 0 to 100 % to the blower regulator via the AC bus (A32n1).Depending on the control voltage, the blower regulator regulates the operating voltage for the blower motor from U = 0 V up to U = 12 V and thus the rotational speed of the blower motor from 0 up to 100 %.
The actuation (operating voltage) of the blower motor is influenced by the following factors:
- Blower selector wheel setting (MANUAL/AUTO)
- Operating functions
- Air distribution
- AC button
- Residual engine heat utilization (without code (494) USA version)
- Mode: heating or cooling
- Coolant temperature
- Vehicle speed
- Vario roof open or close
- Solar radiation
- Fresh air/air recirculation flap position
- Flap positions
- Circuit 15 (blower ON), circuit 50 (starter running, blower off)
The blower output can be increased to match the outside temperature.
To keep the inside temperature constant and the windows clear at low temperatures, the blower output is increased by 15 % at outside temperatures between T = -10 °C and -15 °C.
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 conditioner housing.
The air distribution in the vehicle interior is controlled by corresponding adjustment of the air duct flaps in the air conditioner housing.
- For fresh air and recirculated air control:
- Fresh air and air recirculation flap actuator motor (M16/21)
- for temperature control:
- Left blend air flap actuator motor (M16/28)
- Right blend air flap actuator motor (M16/29)
- for ventilation control:
- Left defroster vent flap actuator motor (M16/13)
- Right defroster vent flap actuator motor (M16/14)
- Left footwell flap actuator motor (M16/15)
- Right footwell flap actuator motor (M16/16)
- Left center air flap actuator motor (M16/23)
- Right center air flap actuator motor (M16/24)
- Air flap actuator motor, left side vent (M16/25)
- Air flap actuator motor, right side vent (M16/26)
Fresh air mode function sequence
The fresh air and recirculated air flap is open and fresh air is delivered into the vehicle interior through the air conditioner housing.
Additional function requirements for air recirculation mode
^ Vario roof closed
^ Window closed
Air recirculation mode function sequence
The air recirculation mode function sequence comprises the following subfunctions:
^ Function sequence, air recirculation mode via air recirculation switch (N22s2)
^ Pollutant-controlled air recirculation mode function sequence
Function sequence, air recirculation mode via air recirculation switch
When the air recirculation switch on the control and operating unit is pressed for t < 1.5 s, the fresh air/air recirculation 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 LED in the air recirculation switch comes on.
In AC mode or at outside temperatures of T < 7 °C, air recirculation mode is switched off after 5 min, and at outside temperatures of T > 7 °C it is switched of after 30 min. The windows are closed automatically by operating the air recirculation switch for t > 1.5 s (convenience recirculation closing).
If the air recirculation switch is operated again for t > 1.5 s, the windows return to their previous position
Windows that were opened manually during air recirculation mode are not returned to their previous positions after air recirculation mode.
With code (460) Canada version and code (494) USA version, convenience recirculation closing is not possible.
The detailed convenience recirculation closing procedure is described in the convenience feature function (KFB).
Additional function requirements for pollutant-controlled air recirculation mode
^ Refrigerant compressor (A9) switched on
^ Defrost mode not active
^ Intake air temperature T > 7 °C
^ Circuit 15 on for at least t = 120
(AAC [KLA] multifunction sensor heating time (B31/1))
Pollutant-controlled air recirculation mode function sequence
The AAC [KLA] multifunction sensor transmits the outside air pollution values to the AAC [KLA] control and operating unit via the AC bus. Starting from a certain pollutant concentration, the fresh air and air recirculation 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. After that, operation continues with 80 % pollutant-controlled recirculated air and after another t = 10 s, as required, with 100 % pollutant-controlled recirculated air. The pollutant- controlled air recirculation mode is not displayed via the LED.
