Regulation of Automatic air conditioning, function

P83.40-5032-79

Function requirements, general

For regulating the climate control:

 Terminal 15 ON

 Automatic air conditioning switched on

For cooling operation:

 Engine running

 Refrigerant compressor switched on (without CODE B09 (Refrigerant compressor with magnetic clutch))

 Refrigerant compressor with magnetic clutch switched on (with CODE B09 (Refrigerant compressor with magnetic clutch))

For evaporator drying process:

 Engine Off

For residual heat utilization:

 Circuit 15 Off or circuit 15C Off

 The electronic ignition lock control unit transmits the status of circuit 15 over the interior CAN to the automatic air conditioning control and operating unit. The CDI control unit (with diesel engine) or the ME-SFI [ME] control unit (with gasoline engine) transmits the "Engine running" signal in vehicles up to 31.05.2013 via the chassis CAN, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. In vehicles as of 01.06.2013, the CDI control unit (with diesel engine) or the ME-SFI [ME] control unit (with gasoline engine) transmits this signal via chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit.

Control, general

The electronic temperature control and regulation of the air distribution in the vehicle interior take place depending on the settings made at the automatic air conditioning control and operating unit, the rear automatic air conditioning operating unit (with CODE 581 (Comfort automatic air conditioning)) and on the variables recorded by different sensors (e.g. interior temperature, outside temperature, coolant temperature, vehicle speed). Determination of these variables is described below.

The automatic air conditioning control and operating unit is connected via interior CAN, climate control LIN and direct lines to the vehicle electronics system. This in turn makes it possible to incorporate relevant parameters in order to improve regulation quality and to lower power consumption.

 If settings are altered on the automatic air conditioning control and operating unit that affect the temperature, the air distribution or the air flow, then the relevant adjustment values are shown briefly in the Audio/COMAND display (A40/8).

The automatic air conditioning control function encompasses the following subfunctions:

 Function sequence for recording and evaluating variables

 Function sequence for AC component actuation

 Fresh air mode function sequence

 Air recirculation mode function sequence

 Function sequence for defroster function

 Function sequence for evaporator drying process

 Function sequence for residual heat utilization (with CODE 581 (Comfort automatic air conditioning))

 Function sequence for shutoff of the air conditioning in the event of a crash as of 01.06.2013

 Function sequence for maximum cooling output (with CODE 494 (USA version))

 Function sequence for ram air operation

Function sequence for recording and evaluating variables

The following variables are recorded and evaluated:

 Outside temperature

 Interior temperature

 Temperature at the air outlets in the vehicle

 Temperature and humidity of windshield (with CODE B03 (ECO start/stop function) in model 207.3 as of 01.12.2009, model 207.4)

 Dew point temperature (with CODE 581 (Comfort automatic air conditioning) up to 31.05.2010)

 Coolant temperature

 Temperature on evaporator

 Refrigerant pressure

 Solar radiation

 Pollutant concentration of outside air (with CODE 581 (Comfort automatic air conditioning))

 Vehicle speed

 Engine speed

 Door status

 Side window position

 Panoramic roof position (with CODE 413 (Panoramic glass sunroof with top sliding sunroof))

 Settings on rear automatic air conditioning operating unit (with CODE 581 (Comfort automatic air conditioning))

 Voice control system (VCS) status (with CODE 525 (MB Audio 50 APS radio) or CODE 511 (Audio 50 APS with DVD changer) or CODE 512 (COMAND APS with DVD changer) or CODE 527 (COMAND APS with single DVD drive (with navigation)) or CODE 528 (COMAND incl. DVD changer) or CODE 531 (COMAND APS))

 Status of the soft top (model 207.4)

Outside temperature

The outside temperature sensor measures the outside temperature. The front SAM control unit reads in the outside temperature sensor signal directly, calculates the outside temperature and sends this via interior CAN to the automatic air conditioning control and operating unit. The automatic air conditioning control and operating unit requires this value to reach the desired interior temperature by adjusting the blend air flaps accordingly. If the vehicle is stationary, the measured temperature can differ considerably from the outside temperature. The outside temperature is therefore only included in the control if the vehicle speed is v  20 km/h. The previously measured temperature is used at speeds of v < 20 km/h and when the ignition is being switched on and off.

Interior temperature

Head area:

The interior temperature is measured by the interior temperature sensor with integrated fan in the overhead control panel electronics. The signals of the interior temperature sensor are read in directly by the automatic air conditioning control and operating unit.

Instrument panel:

The interior temperature is measured in the area of the instrument panel by interior temperature sensor. The signals of the interior temperature sensor are read in directly by the automatic air conditioning control and operating unit.

 Because the interior air is constantly circulated by the fan, a precise temperature measurement is ensured. This enables a temperature control to be achieved that is mainly independent of the airflow conditions in the vehicle interior.

A mean value is calculated from the measurements from the interior temperature sensors. Together with the value of the outside temperature sensor, the mean value is compared to a characteristics map stored in the control and operating unit and used to control the interior temperature.

The mean value of the interior temperature is maintained in the following situations by the automatic air conditioning control and operating unit:

 Side window open

 Door open

This ensures that the air conditioning system immediately continues operation at the set specified temperature.

Temperature at the air outlets in the vehicle

The temperature at the air outlets in the vehicle are recorded by the air outlet temperature sensor. The automatic air conditioning control and operating unit regulates the air outlet temperatures at the respective air outlets.

The signals of the air outlet temperature sensors are read in directly by the automatic air conditioning control and operating unit.

 Up to 31.05.2011 with CODE 581 (Comfort automatic air conditioning), the rear footwell vent air outlet temperature sensor is also installed at the rear air outlet.

Temperature and humidity of windshield (with CODE B03 (ECO start/stop function) in model 207.3 as of 01.12.2009, model 207.4)

The interior humidity/temperature sensor measures the relative air humidity and temperature directly at the inside of the windshield and uses this to determine the dew point temperature. The signals of the interior humidity/temperature sensor are sent via climate control LIN to the automatic air conditioning control and operating unit. If there is a risk of the windows fogging up, appropriate countermeasures are taken such as switching on the refrigerant compressor or starting the engine (with CODE B03 (ECO start/stop function)).

Dew point temperature (with CODE 581 (Comfort automatic air conditioning) up to 31.05.2010)

The dew point sensor uses the ambient temperature and the air humidity to calculate the dew point and sends it to the automatic air conditioning control and operating unit via climate control LIN. When the dew point temperature is reached, the windows and the outside mirrors start to fog up. In order to prevent this, the air conditioning, mirror heater and rear window heater are activated.

Coolant temperature

The temperature of the coolant is recorded by the coolant temperature sensor. The CDI control unit or the ME-SFI [ME] control unit reads in the resistance value directly, uses it to calculate the coolant temperature and, for vehicles up to 31.05.2013, transmits this via the chassis CAN, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. In vehicles as of 01.06.2013, the CDI control unit or the ME-SFI [ME] control unit transmits this signal via the chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. The value is used for controlling the blend air flaps, for regulating the PTC heater booster (with diesel engine) and for actuating the coolant circulation pump (with CODE 581 (Comfort automatic air conditioning)).

Temperature on evaporator

To prevent the evaporator from icing up, the temperature there is measured by the evaporator temperature sensor. The value is read in directly by the automatic air conditioning control and operating unit. If the evaporator temperature drops to approx. T = 2°C, the refrigerant compressor is switched off.

Refrigerant pressure

The refrigerant pressure is recorded by the refrigerant pressure sensor. The front SAM control unit reads in the signal of the refrigerant pressure sensor directly. The front SAM control unit transmits the value of the refrigerant pressure via the interior CAN to the automatic air conditioning control and operating unit. The pressure is compared with a stored temperature/pressure curve. At a refrigerant pressure p < 1.7 or p > 30 bar, the refrigerant compressor is switched off or not activated.

Solar radiation

The sun sensor records the angle of incidence and the intensity of the solar radiation on the vehicle. The automatic air conditioning control and operating unit reads in the signals of the sun sensor directly. The interior temperature and blower speed are adapted according to the values measured. In the event of one-sided solar radiation, an appropriate temperature difference is set between the left and the right specified control temperatures.

Pollutant concentration of outside air (with CODE 581 (Comfort automatic air conditioning))

The pollutant sensor records the following environmental influences:

 Carbon monoxide (CO)

 Nitrogen oxides (NOx)

 Outside dew point temperature

 Relative humidity

 Outside temperature

The automatic air conditioning control and operating unit reads in the signals of the pollutant sensor via the climate control LIN. The automatic air conditioning control and operating unit controls the automatic recirculation depending on read in values.

Vehicle speed

The instrument cluster transmits the vehicle speed via the interior CAN to the automatic air conditioning control and operating unit. The vehicle speed is used to control the ram air function and for internal calculation of the outside temperature.

Engine speed

The engine speed is recorded by the CDI control unit or by the ME-SFI [ME] control unit. The CDI control unit or ME-SFI [ME] control unit transmits the signal in vehicles up to 31.05.2013 via the chassis CAN, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. In vehicles as of 01.06.2013, the CDI control unit or the ME-SFI [ME] control unit transmits the signal via the chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. The engine speed is used among others to regulate the refrigerant compressor.

Door status

The status of each door is determined by the following control units and transmitted via the interior CAN to the AAC control and operating unit:

 Left front door control unit

 Right front door control unit

If the door is open, the automatic air conditioning control and operating unit retains the current blower output in order to avoid unnecessary readjustment in the event of large differences between the air temperature inside and outside the vehicle.

Side window position

The position of the respective side window is determined by the following control units and transmitted via interior CAN to the AAC control and operating unit:

 Left front door control unit

 Right front door control unit

 Rear control unit

Panoramic roof position (with CODE 413 (Panoramic glass sunroof with top sliding sunroof))

The position of the panoramic sliding sunroof is read in by the panoramic sliding sunroof control unit and sent via interior CAN to the automatic air conditioning control and operating unit.

Settings on rear automatic air conditioning operating unit (with CODE 581 (Comfort automatic air conditioning))

The climate control of the rear compartment can be adjusted by the rear passengers via the rear automatic air conditioning operating unit. Operation of the rockers for controlling the temperature and the blower setting on the rear automatic air conditioning operating unit is read in via the climate control LIN by the automatic air conditioning control and operating unit. Using this data, the temperature in the rear is controlled using the rear blend air flap actuator motor. It is actuated via climate control LIN by the automatic air conditioning control and operating unit.

VCS status (with CODE 525 (MB Audio 50 APS radio) or CODE 511 (Audio 50 APS with DVD changer) or CODE 512 (COMAND APS with DVD changer) or CODE 527 (COMAND APS with single DVD drive (with navigation)) or CODE 528 (COMAND incl. DVD changer) or CODE 531 (COMAND APS))

With VCS [SBS] active, the blower output is limited. The radio with auto pilot system or the COMAND controller unit transmits the status of the VCS via the interior CAN to the automatic air conditioning control and operating unit.

Status of the soft top (model 207.4)

The rear control unit sends the status of the soft top via interior CAN to the automatic air conditioning control and operating unit.

Function sequence for AC component actuation

The function sequence for actuating the air conditioning components comprises the following subfunctions:

 Function sequence for actuation of blower motor

 Function sequence for actuation of the air ducting flaps

 Function sequence for actuation of refrigerant compressor

 Function sequence for actuation of combustion engine fan motor and air conditioning with integrated control

 Function sequence, actuation of the PTC heater booster (for diesel engine)

 Function sequence for actuation of the coolant circulation pump (with CODE 581 (Comfort automatic air conditioning))

Function sequence for actuation of blower motor

Ventilation is achieved with the aid of the blower motor. The automatic air conditioning control and operating unit forwards the request directly to the blower regulator, which then actuates the blower motor.

 In vehicles as of 01.06.2013, the blower motor is shut off after an accident with airbag deployment.

 With VCS [SBS] active, the blower output is limited.

 The blower output is limited by the automatic air conditioning control and operating unit in vehicles with code B03 (ECO start/stop function) when the engine stops. The CDI control unit or the ME-SFI [ME] control unit transmits the status "Engine running" in vehicles up to 31.05.2013 via the chassis CAN, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit. In vehicles as of 01.06.2013, the CDI control unit or the ME-SFI [ME] control unit transmits the status via chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit.

Function sequence for actuation of the air ducting flaps

The air distribution in the vehicle interior is controlled by adjusting the air ducting flaps in the air conditioner housing. The automatic air conditioning control and operating unit actuates the following components over the climate control LIN:

Vehicles with CODE 580 (Automatic air conditioning):

 Fresh air/recirculated air flap via the fresh air/recirculated air flap actuator motor (fresh air/recirculated air control)

 Left blend air flap via left blend air flap actuator motor (temperature control)

 Right blend air flap via the right blend air flap actuator motor (temperature control)

 Defroster flap over the defroster flap actuator motor (ventilation control)

 Air distribution flap via the air distribution flap actuator motor (ventilation control)

Vehicles with CODE 581 (Comfort automatic air conditioning):

 Fresh air/recirculated air flap via the fresh air/recirculated air flap actuator motor (fresh air/recirculated air control)

 Left blend air flap via left blend air flap actuator motor (temperature control)

 Right blend air flap via the right blend air flap actuator motor (temperature control)

 Left defroster flap via left defroster flap actuator motor (ventilation control)

 Right defroster flap via right defroster flap actuator motor (ventilation control)

 Left footwell flap via left footwell flap actuator motor (ventilation control)

 Right footwell flap via right footwell flap actuator motor (ventilation control)

 Left center air vent flap via left center air vent flap actuator motor (ventilation control)

 Right center air vent flap via right center air vent flap actuator motor (ventilation control)

 Diffuser flap via the diffuser flap actuator motor (ventilation control)

 Ram air flap via the ram air flap actuator motor (up to 31.05.2010) (ram air control)

 Rear blend air flap over the rear blend air flap actuator motor (temperature control)

 Fresh air/recirculated air flap via the fresh air/recirculated air flap actuator motor (as of 01.06.2010) (ram air control)

 In vehicles as of 01.06.2013, the fresh air/recirculated air flap is closed after an accident with airbag deployment.

 In order to prevent fogging of windows, the defroster flaps are closed t = 2 min. after switching off circuit 15. After starting the engine, the defroster flaps remain in this position for approx. t = 30 s. After that, all adjustments are possible again.

 With "circuit 15 Off", when one of the doors is opened the fresh air/recirculated air flap is set to partial air recirculation by the fresh air/recirculated air flap actuator motor and the ram air flap (with CODE 581 (Comfort automatic air conditioning)) is set to partial air recirculation by the ram air flap actuator motor (up to 31.5.10) or the fresh air/recirculated air flap actuator motor (as of 1.6.10). The door closing forces are thereby reduced. The function can be set with the diagnostic tester.

P83.10-2666-76

Function sequence for actuation of refrigerant compressor

The refrigerant compressor is responsible for induction and compression of the refrigerant. The refrigerant compressor output is continuously regulated up to 100 % via the refrigerant compressor regulating valve by the automatic air conditioning control and operating unit. The automatic air conditioning control and operating unit sends the switch-on request via interior CAN to the front SAM control unit. This receives the request and actuates the refrigerant compressor closed-loop control valve.

With CODE B09 (Refrigerant compressor with magnetic clutch), a magnetic clutch is also installed. This can be used to completely disconnect the refrigerant compressor from the belt drive power flow. This in turn enables additional fuel savings to be made. The automatic air conditioning control and operating unit transmits the request via the interior CAN to the front SAM control unit. This directly actuates the refrigerant compressor magnetic clutch.

The automatic air conditioning control and operating unit also transmits the request for the idle speed increase via the interior CAN, the front SAM control unit and the chassis CAN (up to 31.05.2013) or chassis CAN 1 (as of 01.06.2013) to the ME-SFI [ME] control unit or the CDI control unit. This increases the idle speed in accordance with the additional load that occurs when the refrigerant compressor is switched on.

 In vehicles as of 01.06.2013, the refrigerant compressor is shut off via the refrigerant compressor regulating valve or via the refrigerant compressor magnetic clutch (with CODE B09 (Refrigerant compressor with magnetic clutch)) after an accident with airbag deployment.

Function sequence for actuation of combustion engine fan motor and air conditioning with integrated control

The fan motor is used for cooling the coolant and refrigerant.

The automatic air conditioning control and operating unit calculates the specified fan speed depending on the refrigerant pressure and transmits the request via the interior CAN, the front SAM control unit and the chassis CAN (up to 31.05.2013) or chassis CAN 1 (as of 01.06.2013) to the CDI control unit or the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit calculates the specified fan speed depending on the engine temperature, compares this with the request from the automatic air conditioning control and operating unit and actuates the fan motor accordingly.

Function sequence, actuation of the PTC heater booster (for diesel engine)

The PTC heater booster is actuated by the AAC control and operating unit via the climate control LIN as and when needed.

 In vehicles as of 01.06.2013, the PTC heater booster is switched off after an accident with airbag deployment.

Function sequence for actuation of the coolant circulation pump (with CODE 581 (Comfort automatic air conditioning))

The coolant circulation pump is used to support the coolant circuit, e.g. at low engine speeds, when the engine is stopped (with CODE B03 (ECO start/stop function)) or when the residual heat utilization function is used.

The automatic air conditioning control and operating unit transmits the request for actuation of the coolant circulation pump via the interior CAN to the front SAM control unit. This receives the request and actuates the coolant circulation pump.

Fresh air mode function sequence

The fresh air/recirculated air flap is open and fresh air is delivered into the vehicle interior through the air conditioner housing.

Air recirculation mode function sequence

The air recirculation mode function sequence includes the following subfunctions:

 Function sequence for air recirculation mode using air recirculation mode button

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

Function sequence for air recirculation mode using air recirculation mode button

When the air recirculation mode button on the automatic air conditioning control and operating unit is pressed for t < 1.5 s, the fresh air/recirculated air flap is closed to prevent air entering from outside. The air only circulates in the vehicle interior and unpleasant odors and harmful gases are kept out. The light-emitting diode (LED) above the air recirculation mode button is illuminated during the air recirculation mode.

The automatic air conditioning control and operating unit reads in the status of the air recirculation mode button directly and actuates the fresh air/recirculated air flap actuator motor via climate control LIN.

 The side windows and the panoramic roof (with CODE 413 (Panoramic glass sunroof with top sliding sunroof)) are also closed. If the air recirculation mode button is then pressed for t > 1.5 s, the side windows and the panoramic roof (with CODE 413 (Panoramic glass sunroof with top sliding sunroof)) are moved back to their default positions (provided that they were not manually adjusted during air recirculation mode).

 Detailed information on the convenience feature is available in the separate function description for the "Convenience feature (KFB) function".

 In vehicles with code 460 (Canada version) and CODE 494 (USA version), comfort recirculation closing is not possible.

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

 Refrigerant compressor switched on (without CODE B09 (Refrigerant compressor with magnetic clutch))

 Refrigerant compressor with magnetic clutch switched on (with CODE B09 (Refrigerant compressor with magnetic clutch))

 Defrost mode not active

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

The pollutant sensor records the pollutant levels of the outside air. The automatic air conditioning control and operating unit reads in the signals of the pollutant sensor via the climate control LIN. 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 the pollutant-controlled air recirculation mode exist after the engine is started, a supply of fresh air is first provided for t = 30 s. Operation initially continues with 80 % pollutant-controlled recirculated air and then with 100 % pollutant-controlled recirculated air after another t = 10 s.

 The pollutant-controlled air recirculation mode is not indicated by the LED in the air recirculation mode button.

Function sequence for defroster function

When the "defrost" button is pressed, all air flaps of the air conditioner housing are closed with the exception of the defroster flaps and the fresh air/recirculated air flap. These are fully opened. The defroster flaps are adjusted so that the maximum air flow is directed to the windshield and the front side windows. The blend air flaps are set to full warm air supply. The blower motor is actuated by the automatic air conditioning control and operating unit over the blower regulator to ensure the best possible defrost mode depending on the temperature of the air flowing out. The refrigerant compressor is activated in order to ensure that the air flowing out is dried. The air is dried (cooled) and then heated up to the maximum temperature.

 With CODE 581 (Comfort automatic air conditioning), defrost mode is operated separately for the driver via the left defroster flap actuator motor and for the front passenger via the right defroster flap actuator motor. With CODE 580 (Automatic air conditioning), the regulation for the driver and the front passenger takes place together via the defroster flap actuator motor.

Additional function requirements for evaporator drying process

 Air conditioning was active at least once during the last ignition cycle

 Evaporator temperature T > 3 °C

 Outside temperature T > 20 °C

 Doors closed

 Kilometer reading > 250 km

Function sequence for evaporator drying process

To counteract evaporator odors in the vehicle interior and fogging of windows when starting the air conditioning, an evaporator drying process is performed.

With "engine OFF", a timer is activated in the instrument cluster. Up to 31.05.2013, the "Engine running" status is transmitted by the CDI control unit or by the ME-SFI [ME] control unit via chassis CAN to the instrument cluster. As of 01.06.2013, the status is transmitted by the CDI control unit or the ME-SFI [ME] control unit via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the instrument cluster.

After a waiting time of t = 1 h the instrument cluster transmits the request for the evaporator drying process via the interior CAN to the AAC control and operating unit which then starts the evaporator drying process. For this purpose, the blower is actuated at the slowest speed for t = 30 min.

The automatic air conditioning control and operating unit sends the blower request directly to the blower regulator. The blower regulator actuates the blower motor at the slowest speed.

Function sequence for residual heat utilization (with CODE 581 (Comfort automatic air conditioning))

Pressing the "REST" button (with CODE 581 (Comfort automatic air conditioning)) on the automatic air conditioning control and operating unit switches on the function. The automatic air conditioning control and operating unit transmits the request via the interior CAN to the front SAM control unit, which actuates the coolant circulation pump directly. The coolant circulation pump delivers the still warm (residual heat) coolant through the heat exchanger.

At the same time, the automatic air conditioning control and operating unit sends the ventilation request to the blower regulator, which then actuates the blower motor at reduced power. The intake air from the blower motor is routed past the heater heat exchanger and heated up in the process. The function is terminated after a time of t = 30 min. has elapsed or when the on-board electrical system voltage drops below a certain value.

Function sequence for shutoff of the air conditioning in the event of a crash as of 01.06.2013

To prevent the ingress of noxious gases into the vehicle interior in the event of an accident with airbag deployment, the automatic air conditioning control and operating unit starts the following activities:

 The blower motor is no longer actuated. Air is not circulated in the vehicle interior.

 The fresh air/recirculated air flap is moved to the recirculated air position. Outside air can no longer enter the vehicle interior.

 The refrigerant compressor regulating valve is switched off (without CODE B09 (Refrigerant compressor with magnetic clutch)). The refrigerant compressor no longer circulates the refrigerant.

 The refrigerant compressor magnetic clutch is opened (with CODE B09 (Refrigerant compressor with magnetic clutch)). The refrigerant compressor is no longer driven.

 The positive temperature coefficient heater booster is switched off.

The crash signal is transmitted by the supplemental restraint system control unit via chassis CAN 1, the front SAM control unit and the interior CAN to the automatic air conditioning control and operating unit.

 Detailed information on actuation of the individual components in the air conditioning is available in the "Actuating the air conditioning components" subfunction.

Function sequence for maximum cooling output (with CODE 494 (USA version))

Pressing the "MAX COOL" button causes the blower output to be raised to 100 % and the temperature set to "maximum cold".

Function sequence for ram air operation

The speed-dependent ram air flap is adjusted to prevent the air feed in the vehicle interior from increasing when the speed increases. The higher the speed, the further the ram air flap is closed.

The instrument cluster transmits the vehicle speed signal via the interior CAN to the automatic air conditioning control and operating unit. This actuates the fresh air/recirculated air flap actuator motor (without CODE 581 (Comfort automatic air conditioning)) in a speed-dependent manner. In vehicles with code 581 (Comfort automatic air conditioning), the ram air flap actuator motor (up to 31.05.2010) or the fresh air/recirculated air flap actuator motor (as of 01.06.2010) is actuated in a speed-dependent manner by the automatic air conditioning control and operating unit.