GF83.40-P-2004G Regulation of Automatic Air Conditioning, Function
GF83.40-P-2004G Regulation of Automatic Air Conditioning, Function
MODEL 463.306 /336 /346 up to 31.5.12 as of model year 2011 /YoM 10
MODEL 463.202 /222 /236 /237 up to 31.5.12 as of model year 2009 /YoM 08
MODEL 463.247 /248 /249 /254 /270 /271 /303 /340 /341 up to 31.5.12 as of model year 2007
Automatic air conditioning (without code (HH7) Additional air conditioning in rear)
1 Circuit 15 status
2 Actuation of blower and actuator motors
3 Evaporator temperature
4 Air humidity
5 Window positions
6 Battery voltage
7 Power tilting/sliding roof position (with code (D27) Power tilting/sliding roof)
8 Door status
9 Ambient temperature
10 Refrigerant pressure and refrigerant temperature
11 Actuation of refrigerant compressor
12 Actuating the heater water circulation pump
13 Actuation of cooling fan
14 Coolant temperature
15 Interior temperature
16 Circuit 61 status
17 Circuit status, engine speed
18 Vehicle speed
A1 Instrument cluster
A9 Refrigerant compressor A32m1 Blower motor
A32n1 Blower regulator
B10/6 Evaporator temperature sensor B11/4 Coolant temperature sensor B12/2 Refrigerant pressure and temperature sensor
B14 Outside temperature display temperature sensor B31/2 Air humidity sensor
M2/5 Fresh air/air recirculation flaps actuator motor
M2/6 Left blend air flap actuator
M2/7 Right blend air flap actuator M2/15 Left and right footwell flaps actuator motor
M2/16 Left and right defroster flaps actuator motor
M2/21 Fresh air flaps actuator motor
M4 Auxiliary fan
M13 Heating water circulation pump
N3/9 CDI control unit (with diesel engine)
N3/10 ME-SFI [ME] control unit (with gasoline engine)
N10/1 Front signal acquisition and actuation module (SAM)
N10/2 Rear signal acquisition and actuation module (SAM)
N22 AAC [KLA] control and operating unit
N22b1 Interior air temperature sensor
N69/1 Door control module front left
N69/2 Door control module front right
N69/3 Left rear door control unit (only model 463.236/237/248/249/ 270/271/341/346)
N69/4 Right rear door control unit (only model 463.236/237/248/249/ 270/271/341/346)
N70 Overhead control panel control unit
N70b1 Interior air temperature sensor
N73 EZS control unit
S17/3 Left front door contact switch
S17/4 Right front door contact switch
S17/5 Left rear door contact switch (only model 463.236/237/248/249/ 270/271/341/346)
S17/6 Right rear door contact switch (only model 463.236/237/248/249/ 270/271/341/346)
B Interior CAN
C Drive train CAN
KB AC bus
Function requirements
^ Circuit 15 ON
^ Automatic air conditioning switched on
^ Circuit 61 On (for cooling mode)
^ Refrigerant compressor switched on (for cooling mode)
The status of circuit 15 is sent by the EZS control unit via interior CAN (CAN B).
The status of circuit 61 is sent by the CDI control unit or by the ME-SFI [ME] control unit via drive train CAN (CAN C) to the EZS control unit. It routes the message to the interior CAN. The control and operating unit receives the respective message.
General function sequence regulation
The electronic regulation of the temperature and the air distribution in the interior takes place depending on the settings selected on the control and operating unit and the basic conditions detected by the various sensors (e.g. interior temperature, outside temperature, coolant temperature).
The determination of these variables is described following the description of the adjustments that are relevant for regulation.
The control and operating unit is networked via interior CAN and A/C bus with 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.
Adjustments that are relevant for regulation
^ Automatic regulation
^ Manual regulation
^ Recirculated air function
^ Defrost function
^ Refrigerant compressor switched on or off
Automatic regulation
Additional function requirements
^ Automatic regulation activated by pressing the automatic button (function indicator is on)
Function sequence for automatic regulation
The temperature, air distribution and air volume are regulated depending on the temperature preselection at the control and operating unit and the ambient parameters listed below.
^ Interior temperature
^ Ambient temperature
^ Air humidity of the outside air (dew point temperature)
^ Coolant temperature
^ Vehicle speed
^ Temperature on evaporator
^ Pressure and temperature of the refrigerant
^ Engine speed
The air is cooled down through regulated actuation of the refrigerant compressor. Heating takes place by admixing air heated by the heater heat exchanger through the blend air flaps.
The blower motor is actuated by the control and operating unit via the blower regulator.
Actuation takes place via the following components:
^ Fresh air/air recirculation flaps actuator motor
^ Left blend air flap actuator
^ Right blend air flap actuator
^ Left and right footwell flaps actuator motor
^ Left and right defroster flaps actuator motor
^ Fresh air flaps actuator motor
Manual regulation
Additional function requirements
^ Air distribution and air volume changed manually (Function indicator in automatic button is not on)
Function sequence with manual regulation
The regulation of temperature, air distribution, and air volume takes place depending on the adjustments made on the control and operating unit.
Recirculated air function Additional function requirements
^ Air recirculation mode button pressed (function indicator is on)
Function sequence of the recirculated air function
By activating the function, the fresh air/air recirculation flaps are closed and the air circulates in the vehicle interior.
The time of the recirculated air function is limited in the following cases:
^ The refrigerant compressor is switched off, the recirculated air function is carried out for t = 5 min.
^ The outside temperature is T 7 °C, the recirculated air function is carried out for t = 5 min.
^ The outside temperature is T 7 °C, the recirculated air function is carried out for t = 30 min.
Additional function requirements
^ Defroster button pressed (function indicator is on)
Function sequence of defroster function
By activating the function, the previously made adjustments are superimposed.
The defroster flaps are adjusted by the left and right defroster flaps actuator motor so that the maximum air flow is directed to the windshield and the front side windows.
Refrigerant compressor switched on or off
By pressing the A/C button, the actuation of the refrigerant compressor is deactivated. The other functionalities of the automatic air conditioning continue being available. However, a cool-down below the current outside temperature is not possible.
Determination of the variables for regulating the automatic air conditioning:
^ Interior temperature
The interior temperature is measured by the in-car temperature sensor in the control and operating unit in the area of the dashboard.
The interior temperature is measured by the in-car temperature sensor in the area of the roof. The overhead control panel control unit transmits the interior temperature value via interior CAN to the control and operating unit.
^ Outside temperature
The outside temperature display temperature sensor measures the outside temperature. The temperature value is read in by the front SAM and transmitted via interior CAN to the control and operating unit. The control and operating unit needs this value to reach the desired interior temperature by adjusting the blend air flaps accordingly.
^ Air humidity
The dew point is determined via the dew point sensor. The dew point is needed to regulate the refrigerant compressor. The dew point sensor is read in by the control and operating unit via AC bus.
^ Coolant temperature
The temperature of the coolant is measured by the coolant temperature sensor. It is read in by the CDI control unit or by the ME-SFI [ME] control unit and transmitted to the EZS control unit via drive train CAN. It transmits the value to the control and operating unit via interior CAN.
This value is used to control the blend air flaps and to actuate the coolant circulation pump.
^ Temperature on evaporator
To prevent the evaporator from icing up, the temperature there is measured by the evaporator temperature sensor. The evaporator temperature sensor is read in directly by the control and operating unit.
^ Pressure and temperature of the refrigerant
The pressure and the temperature of the refrigerant are measured by the refrigerant pressure and temperature sensor.
The refrigerant pressure and temperature sensor is read in discretely by the front SAM and forwarded to the control and operating unit via interior CAN.
^ Positions of the windows
The positions of the window are transmitted by the particular door control unit via interior CAN. The control and operating unit needs these values to achieve a higher control quality.
^ Position of the tilting/sliding roof (SHD) (with code (D27) Power tilting/sliding roof)
The position of the tilting/sliding roof is transmitted by the overhead control panel control unit via interior CAN. The control and operating unit needs this value to achieve a higher control quality.
Rear air conditioning (with code (HH7) Additional air conditioning in rear)
1 Circuit 15 status
2 Circuit 61 status
3 Evaporator temperature
4 Actuation of rear air conditioning refrigerant shutoff valve
5 Actuation of blower motor
6 Actuation of air distribution actuator motor
7 A/C status
B Interior CAN
B10/11 Rear air conditioning evaporator temperature sensor
M2/1 Rear blower motor
M16/22 Up/down air distribution actuator motor
N22 AAC [KLA] control and operating unit
N22/4 Rear AC control unit
N29/2 Rear air conditioning electronic blower controller
N73 EZS control unit
Y67 Rear AC refrigerant shutoff valve
Function sequence for regulation of rear air conditioning (with code (HH7) Additional air conditioning in rear)
The rear air conditioning cools the interior air to the temperature level preselected by the rear passengers. The system works depending on the settings selected by the rear passengers as well as the evaporator temperature. The delivered ambient air is cooled and dehumidified in the evaporator here. The air is distributed in the interior via the mixed air vents of the rear air conditioner housing. The temperature of the emitted cold air is monitored by the rear air conditioning evaporator temperature sensor here and shown graphically on the display of the rear air conditioning control unit.
The rear air conditioning control unit receives the circuit status as well as the status of the refrigerant compressor via interior CAN from the AAC [KLA] control and operating unit.
The air distribution is performed via the top and bottom air distribution actuator motor depending on the selected setting.
The rear air conditioner only enables cooling of the ambient air; a temperature increase as well as automatic regulation of the temperature level is not possible.
