Climate Control -- Basic Knowledge -- 215 & 220 Chassis: Other Mercedes-Benz Pullman W221

Ventilation, function - GF83.10-P-2000I

MODEL 220

Ventilation function without rear air conditioning

Air Ventilation Function Diagram Without Rear Air Conditioning. Scheme 92

Ventilation function with rear air conditioning

Air Ventilation Function Diagram With Rear Air Conditioning. Scheme 93

Function

The ventilation

1. keeps the windows from fogging up.
2. supplies fresh air to the vehicle passengers.
3. helps to quickly achieve and maintain a uniform and pleasant temperature in the passenger compartment.

In normal operation, with the vehicle standing still or to increase the air quantity, ventilation is achieved with the support of the blower for the air conditioning (automatic) and blower for the rear air conditioning (with code 582).

Fresh air is sucked in through the air intake in the engine hood and through the fresh air flap in the A/C housing. The air passes through the air ducts to the air outlets into the passenger compartment depending on the settings on the pushbutton control module. In the recirculated air mode the blower sucks air out of the vehicle passenger compartment and conveys it in the recirculated air flap through the A/C housing.

The rear air conditioning operates exclusively with air from the vehicle passenger compartment.

The air passes through ventilation slits below the rear shelf into the trunk and from there passes out of the vehicle through the rear vents.

Ventilation, function - GF83.10-P-2000N

MODEL 215

Ventilation, function

Air Ventilation Function Diagram - Model 215. Scheme 94

Function

The ventilation

1. keeps the windows from fogging up.
2. Supply of fresh air for vehicle passengers.
3. helps to quickly achieve and maintain a uniform and pleasant temperature in the passenger compartment.

Ventilation of the passenger compartment is supported by the blower for the air conditioning (automatic) during normal operation, when the vehicle is standing still or when an increased air flow rate is required.

Fresh air is sucked in through the air inlet in the engine hood and through the fresh air flap in the AC housing. The air flows through the air ducts to the air outlets in the passenger compartment depending on the pushbutton control module setting. In the recirculated air mode air is sucked in from the passenger compartment by the blower through the recirculated air flap and transferred to the AC housing.

The air flows through the ventilation slots below the rear shelf into the trunk and exits the vehicle through the rear vents.

Blower, function - GF83.10-P-2102-02I

Function

The automatic A/C pushbutton control module transfers a control voltage of 0 - 6V to the blower control. This then controls the operating voltage for the blower (0-12 V) depending on the control voltage present. This provides for control of the blower speed from 0 -100 %.

The blower control (operating voltage) is affected by the following factors

1. Blower speed setting (AUTO/manual)
2. Control functions (ON/OUT, EC, REST, air distribution)
3. Mode (heating/air conditioning)
4. Sun intensity
5. Coolant temperature
6. Vehicle speed
7. Position of fresh air/recirculated air flap
8. Position of activated charcoal filter flap
9. Flap positions
10. Number of passengers (via occupied seat recognition feature in front seats)
11. Circuit 15 (blower ON), starter running (blower OFF)

Blower, function - GF83.10-P-2102-02M

Function

The rear A/C pushbutton control module transfers a control voltage of 0 - 6V to the rear blower regulator. This then controls the operating voltage for the rear blower (0 - 12 V) depending on the control voltage present. This provides for control of the blower speed from 0 100 %.

The blower control (operating voltage) is affected by the following factors

1. Blower speed (AUTO/manual)
2. Control functions (ON/OUT, EC, REST, air distribution)
3. Circuit 15 (blower ON), starter running (blower OFF)

Blower regulator, function - GF83.10-P-2103-01I

Function

With the blower buttons ( ) or in the automatic mode a control voltage (0 - 6 V) is transferred from the automatic A/C pushbutton control module to the blower regulator. The latter then regulates the operating voltage (0 - 12 V) according to the control voltage. This provides the control of the blower speed in the range of 0 - 100 %

Scheme 95

Blower regulator, function - GF83.10-P-2103-01M

Function

With the blower buttons ( ) or in the automatic mode a control voltage (0 - 6V) is transferred from the rear A/C pushbutton control module to the rear blower regulator. The latter then regulates the operating voltage for the rear blower (0 - 12 V) depending on the control voltage present. This provides the control of the blower speed in the range of 0 - 100 %

In the automatic mode the control voltage for the rear blower control is calculated according to the control voltage for the automatic A/C read in by the CAN bus.

Center nozzle, function - GF83.10-P-2107-01I

Illustrated on model 220

Function

The air direction can be adjusted as desired upward, downward, to the left, right or to the middle with separately adjustable louvers in the center nozzles (2, 7).

The center nozzles (2, 3, 7, 8) can be opened and closed with the adjustment wheels (4, 6).

To open turn the adjustment wheels (4, 6) upward

Scheme 96

1. Center nozzle closed
2. Pivoting center nozzles (2, 7) are open
3. Pivoting center nozzles (2, 7) and fixed center nozzles (3, 8) are open. see scheme 16: Identifying Center Nozzle Components - Model 220

The temperature of the air exiting from the center nozzle (1) can be controlled with the adjustment wheel (5).

To lower the temperature: turn adjustment wheel (5) in "blue" direction.

Automatic operation: turn adjustment wheel to "A". The indicator lamp (9) above the adjustment wheel (5) comes on. The air quantity and air temperature for the center nozzle (1) are controlled automatically by the pushbutton control module by the center nozzle electronic circuitry.

Side nozzle, function - GF83.10-P-2108-01I

Illustrated on model 220

Function

The direction of the air can be adjusted as desired upward, downward, to the left, right or to the middle with the adjustable louver (2) in the side nozzle.

To open turn adjustment wheel (4) toward outside

1. Side nozzle completely open
2. Side nozzle and air outlet (5) for door nozzle open. Air exits from the door nozzle.

The side nozzle (1) is closed when the adjustment wheel (4) is turned completely to the inside.

Identifying Defroster And Side Nozzles - Model 220. Scheme 97

Rear nozzle, function - GF83.10-P-2111-01I

Illustrated on model 220

Function

The direction of the air can be adjusted as desired upward, downward, to the left and right with two separately adjustable louvers (2).

The rear nozzle (1) can be opened and closed with the adjustment wheel (4). To open turn the adjustment wheel (4) to the left.

Identifying Rear Nozzle Location - Model 220. Scheme 98

Stowage compartment ventilation nozzle, function - GF83.10-P-2112-01I

Function

To open the stowage compartment ventilation nozzle: move lever up

To close the stowage compartment ventilation nozzle: move lever down

The air quantity supplied depends on

1. the air distribution setting
2. the air quantity setting
3. the opening position of the vent nozzles in the armrest.

The air temperature corresponds approx. to that of the air exiting from the center nozzles. It cannot be adjusted separately.

Scheme 99

Extreme temperatures can be present in the stowage compartment due to the close space. For this reason close the vent nozzles when the heater is in operation when transporting goods sensitive to heat.

Do not cover the stowage compartment ventilation with objects.

Defroster nozzle flap actuator motor, function - GF83.10-P-2129-02I

Function

When the defroster button ( ) is pressed on the automatic A/C button control module the defroster vent flap actuation motors are actuated via the A/C bus and electronic stepping motor control module. The defroster vent flap actuation motors therefore control the defroster flaps, which can move to the following positions depending on the requirements

Defroster function

Defroster vent flap 100 % open

REST function

Defroster vent flap open depending on exit temperature

Automatic A/C switched off

Defroster vent flap 100 % open (this emergency operation characteristic ensures that the windshield does not fog up even if a defect is present)

Automatic flap control (AUTO button pressed)

Defroster vent flap open depending on exit temperature

Defroster vent flap control via pushbutton control module (air distribution switch position indicated by hour hand position on 12 hour switch)

Diverter flap actuator motor, function - GF83.10-P-2130-02I

Function

The diverter flap actuator motors are actuated via the center nozzle electronic circuitry control module, the A/C bus and electronic stepping motor control module depending on the desired air exit temperature at the center nozzle.

Diverter flap control via automatic A/C pushbutton control module

Defrost function

Diverter flap open 0% (only when center nozzle is in AUTO position)

REST function

Automatic (only when center nozzle is in AUTO position)

Automatic A/C switched off

Diverter flap open 0%

Automatic diverter flap control

The diverter flaps are controlled separately on the left and right. The diverter flaps open beginning at an outdoor temperature > 20 °C.

If the temperature difference between the temperature measured by the in-car temperature sensor and that set on the pushbutton control module is within the adjustment range of + 1 to + 6 °C, the diverter flap is opened linearly from 0 - 100 %.

Diverter flap control via the center nozzle

In the manual mode the diverter flap positions can be set with the three selection dials on the center nozzle.

Blend flap actuator motor, function - GF83.10-P-2131-02I

Function

The blend flap actuator motors are controlled by the electronic center nozzle control module, A/C bus and electronic stepping motor control module depending on the desired air outlet temperature at the center nozzle.

Blend flap control via automatic A/C pushbutton control module

Defrost-function

Blend flap open 0% (only when center nozzle is in AUTO position)

REST-function

Dependent on exit temperature (only when center nozzle is in AUTO position)

Automatic A/C switched off

Blend flap open 0%

Blend flap control via exit temperatures

If the center nozzle is in the AUTO mode, the blend flaps are regulated depending on the exit temperatures and the set air quantity potentiometer for the center nozzle.

Blend flap control via center nozzle

In the center nozzle manual mode the blend flaps are set by the left and right selection dials (potentiometer) for the center nozzle.

Left/right selection dial (potentiometer) 0-100 % corresponds to left/ right blend flap position of 0-100 % (linear).

Footwell flap actuator motor, function - GF83.10-P-2132-02I

Function

The footwell flap actuator motors are controlled via the A/C bus and electronic stepping motor control module by turning the air distribution knob on the automatic A/C pushbutton control module. The footwell flap actuator motors thereby control the footwell flaps, which can assume the following positions depending on the settings.

Circuit logic

1. Footwell and rear footwell closed = 50%
2. Footwell completely open and rear footwell closed = 100% (vehicles with rear air conditioning)
3. Footwell and rear footwell completely open = 0% (vehicles without rear air conditioning)

Control for "DEFROST" 50%

Control for "REST" depending on exit temperature

Control for "0" 50%

Control for "AUTO" depending on exit temperature

Footwell flap actuator motor control via automatic A/C pushbutton control module - without rear air conditioning

(air distribution switch position indicated by hour hand position on 12 hour clock)

Footwell flap actuator motor control via automatic A/C pushbutton control module - with rear air conditioning (air distribution switch position indicated by hour hand position on 12 hour clock)

Footwell flap actuator motor, function - GF83.10-P-2132-02N

Function

The footwell flap actuator motors are controlled via the A/C bus and electronic stepping motor control module by turning the air distribution knob on the automatic A/C pushbutton control module.

The footwell flap actuator motors thereby control the footwell flaps, which can assume the following positions depending on the settings.

Circuit logic

1. Footwell and rear footwell closed = 50%
2. Footwell and rear footwell completely open = 0%

Control for "DEFROST" 50%

Control for "REST" depending on exit temperature

Control for "0" 50%

Control for "AUTO" depending on exit temperature

Footwell flap actuator motor control via automatic A/C pushbutton control module

(air distribution switch position indicated by hour hand position on 12 o'clock)

Door vent, function - GF83.10-P-2133-02I

Illustrated on model 220

Function

The air to the door vents (1) can be controlled by opening the side nozzle adjustment wheel (2).

Settings on side nozzle adjustment wheel (2)

Side nozzle completely open

Scheme 100

1. Side nozzle and air outlet to door vent (1) open. Air exits at the door vent. see scheme 36: Identifying Door Vent Location - Model 220

Rear compartment side vent position - GF83.10-P-2134-01I

The rear side outlet (1) is located on the left and right B-pillar in the level of the front head restraints.

Identifying Rear Compartment Side Vent Position. Scheme 101

Rear compartment side vent function - GF83.10-P-2134-02I

Function

The direction of the air can be varied via the louver (2) on the rear side outlets (1). To open, turn the adjuster (3) towards the side window.

Identifying Rear Compartment Side Vent Position. Scheme 102

Multifunction sensor function - GF83.10-P-2135-02I

Function

The multifunction sensor records the humidity, the ambient temperature and the pollutant concentration of carbon monoxide (CO) and nitrogen oxide (NOx) of the outside air. From the first two values it calculates the dew point and transmits this with the other values to the AAC pushbutton control module via the A/C bus. By means of this sensor an A/C compressor control to suit demand is permitted as a function of humidity.

Control of fresh air/recirculated air flap via the multifunction sensor

Conditions

Scheme 103

1. Outside temperature >7 °C
2. Activated charcoal filter button ( illuminated)

If the actual pollutant concentration outside the vehicle determined by the multifunction sensor is above an assumed mean interior air quality, a signal is sent to the pushbutton control module via the air conditioning bus which switches the system to 100% recirculated air. As soon as the pollutant concentration outside the vehicle is below the assumed mean interior air quality again, the system is run with fresh air again (exceptions: recirculated air operated manually: automatic recirculated air due to high outside temperature).

Heating circuit function - GF83.20-P-2003I

MODEL 220

Identifying HVAC Components. Scheme 104

Identifying Heater Core Location In Rear A/C Housing. Scheme 105

Function

The coolant pump (5) pumps cold coolant through the engine. There the coolant absorbs engine heat and is heated up. Then the heated up coolant is led through the heater heat exchanger (8) where the heat is released into the interior air. The quantity of coolant flowing through the heater heat exchanger (8) is controlled by the duo valves (A31y1 and A31y2) in the coolant return (A). The quantity of coolant can be controlled separately for the left and right side.

The coolant flows back to the coolant pump (5) via the coolant return (A). A far higher proportion of the coolant does not flow through the heater but from the engine to the coolant thermostat (4). Depending on the water temperature it routes the water through the radiator (3) or straight on to the coolant pump (5).

Vehicles with rear air conditioning (code 582)

On vehicles with rear air conditioning (code 582), heated up coolant is also supplied to the heater heat exchanger (9) in the rear. The quantity of coolant flowing through the heater heat exchanger (9) in the rear is controlled by the duo valves (A31y1 and A31y2) in the coolant return (A). The quantity of coolant can also be controlled separately for the left and right side.

Heater circuit, function - GF83.20-P-2003N

MODEL 215

Heater Circuit Function Diagram - Model 215. Scheme 106

Function

The coolant pump (5) pumps cold coolant through the engine. There, the coolant absorbs heat from the engine and is heated up. The heated coolant then flows through the heater core (8) where the heat is transferred to the interior air. The coolant quantity flowing through the heat exchanger (8) is controlled by the duovalves (A31y1, A31y2) in the coolant return (A). The coolant quantity can be controlled separately for the left and right sides.

The coolant flows through the coolant return (A) back to the coolant pump (5). The major portion of the coolant flows from the engine to the thermostat (4) rather than through the heater. Depending on the water temperature, the thermostat allows the water to flow to the radiator (3) or directly on to the coolant pump (5).

Duovalve, function - GF83.20-P-2100-01I

Function

The duovalves for the automatic air conditioning are controlled directly by the automatic A/C pushbutton control module using on/off control and control the coolant flow through the heater core separately for the left and right side. The closing and opening times of the duovalves per cycle depend upon the deviation between the actual temperature and the set temperature.

Control principle

The electro magnetic coil in the duovalves is actuated by the automatic A/C pushbutton control module. This allows the hot water quantity flowing through the heater core to be controlled separately for the left and right side. The duovalves are open when not under power.

Control of duovalves by automatic A/C pushbutton control module

Duovalve, function - GF83.20-P-2100-01M

Function

The duovalves for the rear air conditioning are controlled directly by the rear air conditioning pushbutton control module and control the coolant flow through the rear heater core separately for the left and right side.

The closing and opening times of the duovalves per cycle depend on the temperature setting.

Control principle

The electro-magnetic coils in the duovalves are controlled digitally by the rear air conditioning pushbutton control module. This allows the hot water quantity flowing through the rear heater core to be controlled separately for the left and right side.

The duovalves are open when not under power.

Control of duovalves by rear air conditioning A/C pushbutton control module

Heater core, function - GF83.20-P-2101-01I

Function

The heated coolant flows through the heater core for the left and right side separately. The banks of aluminum tubes and louvers transfer the heat to the outside where it is absorbed by the air flowing by on its way to the various defroster ventilation and heater vents in the vehicle passenger compartment.

Heater core, function - GF83.20-P-2101-01M

Function

The heated coolant flows through the rear heater core for the left and right side separately. The banks of aluminum tubes and louvers transfer the heat to the outside where it is absorbed by the air flowing by on the way to the rear compartment nozzles and/or rear footwell outlets in the rear passenger compartment.

Coolant circulation pump, function - GF83.20-P-2102-01I

Function

The quantity of coolant circulating through the heater core when the engine is running depends on the coolant pump. The coolant circulation pump ensures that a uniform flow of bubble-free water is present in the heater core even at low engine speeds. Actuation of the coolant circulation pump is controlled by the automatic A/C control module, CAN bus and right signal-acquisition and actuation module.

Control of coolant circulation pump by automatic A/C pushbutton control module.

Coolant circulation pump, function - GF83.20-P-2102-01M

Function

The quantity of coolant circulating through the rear heater core with the engine running depends on the coolant pump. The coolant circulation pump ensures that a uniform quantity of bubble-free water flows through the rear heater core even at low engine speeds. The coolant circulation pump is controlled directly by the rear A/C pushbutton control module.

Control of coolant circulation pump by rear A/C pushbutton control module

Fresh air/recirculated air flap, function - GF83.20-P-2104-02I

Illustrated on model 220

Function

Identifying Fresh Air/Recirculated Air Flap Location - Model 220. Scheme 107

Function

In a the fresh air mode ( not burning) the fresh air flap (1) is open and the recirculated air flap (2) closed. Fresh air is sucked into the A/C housing by the blower

If the automatic A/C pushbutton control module is switched over to recirculated air, the electric actuator motor and linkage (4) close the fresh air flap (1) and simultaneously open the recirculated air flap (2). Air is sucked out of the vehicle passenger compartment into the A/C housing by the blower.

The system switches over automatically from recirculated air to fresh air

1. after 30 minutes at outdoor temperatures above approx. 5 °C
2. after 5 minutes at outdoor temperatures below approx. 5 °C
3. after 5 minutes when is burning.

At high outdoor temperatures the system automatically switches over to 80 % recirculated air. After approx. 30 minutes the system switches to fresh air.

The system can also switch over to recirculated air automatically via the multifunction sensor when the carbon monoxide (CO) or nitric oxide (NOX) levels increase in the outside air. This pollutant-controlled recirculated air mode is not possible when the lamp is on or the outdoor temperature has dropped to below 5 °C

Air distribution switch, function - GF83.25-P-2101-01I

Function

The air distribution switch is combined with the AUTO button ( ). The air distribution can be set manually or automatically

1. Manual (automatic button not pressed) Turn ring around automatic button Indicated by red dot of light and white printed notch
2. Automatic (automatic button pressed) Display indicated by light "AUTO" symbol in display

The various actuator motors can be controlled via the A/C bus and electronic stepping motor circuitry for distribution of the air by turning the air distribution switch on the automatic A/C pushbutton control module.

The following basic air distribution settings are available and are indicated by the LED's arranged in a circular pattern

Scheme 108

Scheme 109

1. Air outlet at center, side and door nozzles
2. Air outlet at center, side and door, footwell and defroster nozzles
3. Air outlet at center, side, door and defroster nozzles
4. Air outlet at center, side, door and footwell nozzles

In addition to the four basic settings listed above 8 intermediate settings can also be selected, which are also indicated by the LED's.

Fresh air/recirculated air flap actuator motor, function - GF83.30-P-2105-02I

Function

When the recirculated air button ( ) on the automatic A/C control module is pressed the fresh air/recirculated air flap actuator motor is actuated via the A/C bus and electronic stepping motor

In the recirculated air mode the recirculated air flap is opened and the fresh air flap closed.

In the fresh air mode the fresh air flap is opened and the recirculated air flap is closed.

Control of fresh air/recirculated air flap via automatic A/C pushbutton control module

When the recirculated air button ( ) on the automatic A/C pushbutton control module is actuated manually the system switches immediately to 100% recirculated air for a limited time. This is indicated by the function indicator LED

The following applies for the time limit

1. Manual recirculated air mode and simultaneously EC mode: 100% recirculated air possible for 5 minutes.
2. Manual recirculated air mode, A/C operation and outdoor temperature less than 7 °C: 100% recirculated air possible for 5 minutes.
3. Manual recirculated air mode, A/C mode and outdoor temperature greater than 7°C: 100 % recirculated air possible for 30 minutes.

Control of fresh air/recirculated air flap via temperature

The automatic recirculated air mode is dependent on the outdoor temperature, temperature setting and passenger compartment temperature. Automatic recirculated air is not indicated by the function indicator LED. In the EC mode automatic recirculated air is not possible.

The following applies for the time limit

1. After switching the ignition ON 100% recirculated air is possible once for a fixed time of 30 minutes.
2. After expiration of this time the system switches over to 80 % recirculated air or fresh air depending on the control setting.
3. After this switchover automatic operation with 100% recirculated air is no longer possible, even when the 100% threshold is exceeded, until the ignition has been switched off and back on again.

Control of fresh air/recirculated air flap via multifunction sensor

If the pollutant concentration actually present and measured by the multifunction sensor outside of the vehicle is above an assumed, average interior air quality, the system switches over to 100 % recirculated air. As soon as the pollutant concentration present outside of the vehicle decreases to below the assumed, average interior air quality, the system switches back over to fresh air (exception: manually switched recirculated air; automatic recirculated air due to high outdoor temperature).

Activated charcoal filter, function - GF83.30-P-2113-02I

Function

The charcoal filter consists of a number of so-called splitter absorbers, which are distributed uniformly on an air-permeable carrier mat, continuously absorb odors and pollutants and release them again after a certain time in very small concentrations. Fresh air as well as recirculated air is filtered.

In the activated charcoal filter mode the blower speed is increased slightly.

The activated charcoal filter can be switched on manually with the activated charcoal filter button ( )

Automatic air conditioning (AAC), function - GF83.40-P-0001I

MODEL 220

Function

The automatic air conditioning (AAC) has an electronically controlled cooling, heating and ventilation system and can be summarized under the following subfunctions.

1. Ventilation The ventilation system looks after the air distribution in the vehicle interior. Ventilation is achieved with the assistance of the automatic air conditioning blower or the rear air conditioning blower in normal mode, when the vehicle is stationary or in order to increase the air quantity. The air is distributed in the vehicle interior via air distribution flaps. In order to prevent the windows from fogging, the front footwell flaps and the rear footwell flaps are fully opened for 30 seconds after the ignition has been switched on. If the vehicle has a rear air conditioning system, only the front footwell flaps are opened. The rear footwell flaps remain closed.
2. Automatic air conditioning temperature control The desired temperature is reached or held constant by cooling or heating the air. Accurate temperature control is achieved by reading in the measurements from various temperature sensors.
3. Automatic air conditioning control Electronic control of the automatic air conditioner takes place using several control modules that are interconnected via the interior bus (CAN Class B). The CAN data bus is a bidirectional bus, i.e. every control module that is connected receives and sends information.
4. Automatic air conditioning pushbutton control module The automatic air conditioning can be operated by the driver by pressing various buttons. The pushbutton control module also reads in various sensor signals, processes them and actuates automatic air conditioning components.
5. Rear air conditioning pushbutton control module The rear air conditioning can be operated by the passenger in the back by pressing various buttons. The pushbutton control module also directly reads in various sensor signals, processes them and actuates rear automatic air conditioning components.
6. Heater circuit Coolant is heated by the engine. Then the heated coolant is led through the heat exchanger (and also through the rear heater heat exchanger in vehicles with rear air conditioning "code 582"), where the heat is given off into the interior air. The coolant returns to the coolant pump via the heater return.
7. Refrigerant circuit The refrigerant compressor compresses the gaseous refrigerant, which heats up, is led to the condenser and is therefore cooled down. After cleaning in the fluid reservoir, the liquid refrigerant is injected into the evaporator core (into the rear evaporator core in vehicles with rear air conditioning). The refrigerant evaporates and cools down. The refrigerant compressor draws in the refrigerant, which has become gaseous again due to heat absorption.
8. Residual engine heat utilization Residual engine heat utilization makes it possible to heat the vehicle even if the ignition is OFF. To do so the system utilizes the residual heat from the engine and guides it via the blower into the passenger compartment.

Automatic air conditioning (auto A/C), interlinkage of components - GF83.40-P-0001-02I

Temperature control interlinkage

Identifying Temperature Control Interlinkage Components. Scheme 110

Interlinkage A/C compressor control

Automatic Air Conditioning Control Function Diagram - Model 215. Scheme 111

Engine/AC electric fan control module interlinkage

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor. Scheme 112

Temperature control interlinkage

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor. Scheme 113

Convenience locking interlinkage

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor. Scheme 114

Automatic air conditioning (AAC), function - GF83.40-P-0001N

MODEL 215

Function

The automatic air conditioning (AAC) has an electronically controlled cooling, heating and ventilation system and can be summarized under the following subfunctions.

1. Ventilation The ventilation system looks after the air distribution in the vehicle interior. Ventilation is achieved with the support of the automatic air conditioning blower during normal operation, when the vehicle is stationary or to increase the air flow. The air is distributed in the vehicle interior via air distribution flaps. In order to prevent the windows from fogging, the front footwell flaps are fully opened for 30 seconds after the ignition has been switched on.
2. Automatic air conditioning temperature control The desired temperature is reached or held constant by cooling or heating the air. Accurate temperature control is achieved by reading in the measurements from various temperature sensors.
3. Automatic air conditioning control Electronic control of the automatic air conditioning (AAC) takes place using several control modules that are interconnected via the interior bus (CAN Class B). The CAN data bus is a bidirectional bus, i.e. every control module that is connected receives and sends information.
4. Automatic air conditioning pushbutton control module The automatic air conditioning can be operated by the driver by pressing various buttons. The pushbutton control module also reads in various sensor signals, processes them and actuates automatic air conditioning components.
5. Residual engine heat utilization Residual engine heat utilization makes it possible to heat the vehicle even if the ignition is OFF. To do so the system utilizes the residual heat from the engine and guides it via the blower into the passenger compartment.
6. Heater circuit Coolant is heated by the engine. Subsequently the heated refrigerant is led through the heater heat exchanger, where the heat is given off into the interior air. The coolant returns to the coolant pump via the heater return.
7. Refrigerant cycle The refrigerant compressor compresses the gaseous refrigerant, which heats up, is led to the condenser and is thereby cooled down. After cleaning in the fluid reservoir, the liquid refrigerant is injected into the evaporator core. The refrigerant evaporates and cools down. The refrigerant compressor draws in the refrigerant, which has become gaseous again due to heat absorption.

Automatic air conditioning (auto A/C), interlinkage of components - GF83.40-P-0001-02N

Temperature control interlinkage

Identifying Automatic Air Conditioning Housing Location - Model 220. Scheme 115

Interlinkage A/C compressor control

Identifying A/C Compressor Control Interlinkage Components. Scheme 116

Engine/AC electric fan control module interlinkage

Identifying Automatic Air Conditioning (AAC) Cooling Mode, Interior Heated Up. Scheme 117

Automatic air conditioning pushbutton control module, function - GF83.40-P-2000I

MODEL 220 up to 31.5.01

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor. Scheme 118

Function

The automatic air conditioning pushbutton control module (N22) makes it possible to make adjustments coming from the driver such as

Scheme 119

1. Interior temperature preselection by pressing the cold/hot temperature buttons ( ) separate for left and right
2. Manual/automatic air quantity by pressing the blower button ( )
3. Manual air distribution by turning the air distribution switch, and automatic air distribution/ blower speed by pressing the Auto button ( ) that is combined with the air distribution switch
4. Recirculating air system by pressing the recirculating air pushbutton ( )
5. Activating the residual engine heat utilization system with the ignition switched off by pressing the REST button ( )
6. Switching off the cooling by pressing the EC button ( )
7. defrost function by pressing the defroster button ( )
8. Turn on activated charcoal filter by pressing the activated charcoal filter pushbutton ( ).
9. Switching ON/OFF by pressing the ON/OFF button ( )
10. Heating the rear window by pressing the rear window heater button ( )

The control module integrated in the automatic air conditioning pushbutton control module (N22) also performs the following system changes

1. direct: duo valves; blower regulator
2. via the CAN BUS: refrigerant compressor; in-car temperature sensor; hot water circulation pump; engine/climate control electric fan, rear window heater
3. via the AC bus: Center nozzle electronics; actuator motor electronics with 10 connected actuators for air distribution

The following sensor signals are read in by the automatic air conditioning control module

1. direct: left and right heat exchanger temperature sensor; evaporator core temperature sensor
2. via the CAN BUS: ambient air temperature sensor; refrigerant temperature sensor; refrigerant pressure sensor
3. via the overhead control panel: interior temperature sensor
4. via the electronic ignition lock control module: battery voltage; coolant temperature sensor; engine speed
5. via the instrument cluster: vehicle speed
6. via the AC bus: sun sensor, multifunction sensor, potentiometer in center nozzle

The automatic air conditioning control module reads in the window, door and sliding/tilting roof settings in order to achieve better control quality when they are open.

The front seat occupation signals are sent to the automatic air conditioning control module by the front seat control modules via the CAN bus. The more people in the vehicle, the faster the basic automatic blower speed, for example.

The following sensor signals are sent via the CAN bus by the automatic air conditioning control module

1. Sun sensor values (the overhead operating unit reads in these values for the automatic light control in order to achieve a better redundancy for the system)
2. Dewpoint temperature (the front door control modules read this value in for appropriate control of the heated outside mirror)
3. Seat ventilation (the blower speed that has been set by the automatic air conditioning pushbutton control module is read in by the front seat control module in order to adapt the seat ventilation)

In vehicles with rear air conditioning (code 582)

Communication between the automatic air conditioning pushbutton control module and the rear air conditioning pushbutton control module.

1. Temperature control: The automatic air conditioning pushbutton control module reads in all the rear air conditioning pushbutton control module settings and internally calculates the required blow-in temperatures for the entire interior. The values calculated for the rear left and right are sent to the rear air conditioning pushbutton control module, which regulates the blow-in temperatures itself. If the rear seats are unoccupied (detected via buckle), the temperature control is automatically set to 22 °C.
2. Blower control: If the rear air conditioning pushbutton control module is in automatic blower mode, the front blower level is taken over.
3. Remote control of rear air conditioning pushbutton control module by automatic air conditioning pushbutton control module: If the blower button on the automatic air conditioning pushbutton control module is held down in the AUTO position for approx. 1 second, a control module symbol appears in the front display together with the rear air conditioning settings. These settings can then be modified from the front. The rear air conditioning can also be switched off using the ON/OFF button ( ). The function is automatically exited if no adjustments are made for 3 seconds.

Automatic air conditioning pushbutton control module, function - GF83.40-P-2000IA

MODEL 220 as of 1.6.01

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor (As Of 1.6.01). Scheme 120

Function

The automatic air conditioning pushbutton control module (N22) makes it possible to make adjustments coming from the driver such as

1. Interior temperature preselection by pressing the cold/hot temperature buttons ( ) separate for left and right
2. Manual/automatic air quantity by pressing the blower button ( )
3. manual air distribution by turning the air distribution switch, and automatic air distribution/ blower speed by pressing the Auto button ( ) that is combined with the air distribution switch
4. Recirculating air system by pressing the recirculating air pushbutton ( )
5. Activating the residual engine heat utilization system with the ignition switched off by pressing the REST button ( )
6. Switching off the cooling by pressing the AC OFF button ( )
7. defrost function by pressing the defroster button ( )
8. Operating the activated charcoal filter by pressing the activated charcoal filter pushbutton ( ).
9. Switching ON/OFF by pressing the ON/OFF button ( )
10. Heating the rear window by pressing the rear window heater button ( )

The control module integrated in the automatic air conditioning pushbutton control module (N22) also performs the following system actuations

1. direct: duo valves; blower regulator
2. via the CAN BUS: refrigerant compressor; in-car temperature sensor; hot water circulation pump; engine/climate control electric fan, rear window heater
3. via the AC bus: center nozzle electronics; actuator motor electronics with 10 connected actuators for air distribution

The following sensor signals are read in by the automatic air conditioning control module

1. direct: left and right heat exchanger temperature sensor; evaporator core temperature sensor
2. via the CAN BUS: ambient air temperature sensor; refrigerant temperature sensor; refrigerant pressure sensor
3. via the overhead control panel: interior temperature sensor
4. via the electronic ignition lock control module: battery voltage; coolant temperature sensor; engine speed
5. via the instrument cluster: vehicle speed
6. via the AC bus: sun sensor, multifunction sensor, potentiometer in center nozzle

The automatic air conditioning control module reads in the window, door and sliding/tilting roof settings in order to achieve better control quality when they are open.

The front seat occupation signals are sent to the automatic air conditioning control module by the front seat control modules via the CAN bus. The more people in the vehicle, the faster the basic automatic blower speed, for example.

The following sensor signals are sent via the CAN bus by the automatic air conditioning control module

1. Sun sensor values (the overhead operating unit reads in these values for the automatic light control in order to achieve a better redundancy for the system))
2. Dewpoint temperature (the front door control modules read this value in for appropriate control of the heated outside mirror)
3. Seat ventilation (the blower speed that has been set by the automatic air conditioning pushbutton control module is read in by the front seat control module in order to adapt the seat ventilation)

In vehicles with rear air conditioning (code 582)

Communication between the automatic air conditioning pushbutton control module and the rear air conditioning pushbutton control module.

1. Temperature control: The automatic air conditioning pushbutton control module reads in all the rear air conditioning pushbutton control module set points and internally calculates the required blow-in temperatures for the entire interior. The values calculated for the rear left and right are sent to the rear air conditioning pushbutton control module, which regulates the blow-in temperatures itself. If the rear seats are unoccupied (detected via buckle), the temperature settings are taken over from the automatic air conditioning pushbutton control module.
2. Remote control of rear air conditioning pushbutton control module by automatic air conditioning pushbutton control module: If the blower button on the automatic air conditioning pushbutton control module is held down in the AUTO position for approx. 1 second, a control module symbol appears in the front display together with the rear air conditioning settings. These settings can then be modified from the front. The rear air conditioning can also be switched off using the ON/OFF button ( ). The function is automatically exited if no adjustments are made for 3 seconds.

Automatic air conditioning pushbutton control module, function - GF83.40-P-2000N

MODEL 215 up to 31.5.01

Identifying Automatic A/C Pushbutton Control Module And In-Car Temperature Sensor. Scheme 121

Function

The automatic air conditioning pushbutton control module (N22) makes it possible to make adjustments coming from the driver such as

1. Interior temperature preselection by pressing the cold/hot temperature buttons ( ) separate for left and right
2. Manual/automatic air quantity by pressing the blower button ( )
3. Manual air distribution by turning the air distribution switch, and automatic air distribution/ blower speed by pressing the Auto button ( ) that is combined with the air distribution switch
4. Recirculating air system by pressing the recirculating air pushbutton ()
5. Activating the residual engine heat utilization system with the ignition switched off by pressing the REST button ( )
6. Switching off the cooling by pressing the EC button ( )
7. Defrost function by pressing the defroster button ( )
8. Operating the activated charcoal filter by pressing the activated charcoal filter pushbutton ( )
9. Switching ON/OFF by pressing the ON/OFF button ( )
10. Heating the rear window by pressing the rear window heater button ( )

The control module integrated in the automatic air conditioning pushbutton control module (N22) also performs the following system actuations

1. direct: duo valves; blower regulator
2. via the CAN BUS: refrigerant compressor; in-car temperature sensor; hot water circulation pump; engine/climate control electric fan, rear window heater
3. via the AC bus: center nozzle electronics; actuator motor electronics with 10 connected actuators for air distribution

The following sensor signals are read in by the automatic air conditioning control module

1. direct: left and right heat exchanger temperature sensor; evaporator core temperature sensor
2. via the CAN BUS: ambient air temperature sensor; refrigerant temperature sensor; refrigerant pressure sensor
3. via the overhead control panel: interior temperature sensor
4. via the electronic ignition lock control module: battery voltage; coolant temperature sensor; engine speed
5. via the instrument cluster: vehicle speed
6. via the AC bus: sun sensor, multifunction sensor, potentiometer in center nozzle

The automatic air conditioning control module reads in the window, door and sliding/tilting roof settings in order to achieve better control quality when they are open.

The front seat occupation signals are sent to the automatic air conditioning control module by the front seat control modules via the CAN bus. The more people in the vehicle, the faster the basic automatic blower speed, for example.

The following sensor signals are sent via the CAN bus by the automatic air conditioning control module

1. Sun sensor values (the overhead operating unit reads in these values for the automatic light control in order to achieve a better redundancy for the system))
2. Dewpoint temperature (the front door control modules read this value in for appropriate control of the heated outside mirror)
3. Seat ventilation (the blower speed that has been set by the automatic air conditioning pushbutton control module is read in by the front seat control module in order to adapt the seat ventilation)

Automatic air conditioning pushbutton control module, function - GF83.40-P-2000NA

MODEL 215 as of 1.6.01

Identifying Receiver/Drier, Refrigerant Temperature And Pressure Sensor Location - Model 220. Scheme 122

Function

The automatic air conditioning pushbutton control module (N22) makes it possible to make adjustments coming from the driver such as

1. Interior temperature preselection by pressing the cold/hot temperature button ( ) separate for left and right
2. Manual/automatic air quantity by pressing the blower button ( )
3. Manual air distribution by turning the air distribution switch, and automatic air distribution/blower speed by pressing the Auto button ( ) that is combined with the air distribution switch
4. Recirculating air system by pressing the recirculating air pushbutton ()
5. Activating the residual engine heat utilization system with the ignition switched off by pressing the REST button ( )
6. Switching off the cooling by pressing the AC OFF button ( )
7. Defrost function by pressing the defroster button ( )
8. Operating the activated charcoal filter by pressing the activated charcoal filter pushbutton ( )
9. Switching ON/OFFby pressing the ON/OFF button ( )
10. Heating the rear window by pressing the rear window heater button ( )

The control module integrated in the automatic air conditioning pushbutton control module (N22) also performs the following system actuations

1. direct: duo valves; blower regulator
2. via the CAN BUS: refrigerant compressor; in-car temperature sensor; hot water circulation pump; engine/climate control electric fan, rear window heater
3. via the AC bus: center nozzle electronics; actuator motor electronics with 10 connected actuators for air distribution

The following sensor signals are read in by the automatic air conditioning control module

1. direct: left and right heat exchanger temperature sensor; evaporator core temperature sensor
2. via the CAN BUS: ambient air temperature sensor; refrigerant temperature sensor; refrigerant pressure sensor
3. via the overhead control panel: interior temperature sensor
4. via the electronic ignition lock control module: battery voltage; coolant temperature sensor; engine speed
5. via the instrument cluster: vehicle speed
6. via the AC bus: sun sensor, multifunction sensor, potentiometer in center nozzle

The automatic air conditioning control module reads in the window, door and sliding/tilting roof settings in order to achieve better control quality when they are open.

The front seat occupation signals are sent to the automatic air conditioning control module by the front seat control modules via the CAN bus. The more people in the vehicle, the faster the basic automatic blower speed, for example.

The following sensor signals are sent via the CAN bus by the automatic air conditioning control module

1. Sun sensor values (the overhead operating unit reads in these values for the automatic light control in order to achieve a better redundancy for the system))
2. Dewpoint temperature (the front door control modules read this value in for appropriate control of the heated outside mirror)
3. Seat ventilation (the blower speed that has been set by the automatic air conditioning pushbutton control module is read in by the front seat control module in order to adapt the seat ventilation)

Refrigerant circuit, function - GF83.40-P-2001I

MODEL 220

Identifying Stepper Motor Electronics Control Module Components Location. Scheme 123

The A/C compressor (1) is driven by the engine and compresses the gaseous refrigerant which heats up, flows to the condenser (2) where it is cooled down. The heat from compression is removed from the refrigerant by the surface of the condenser (2). As it cools the refrigerant liquefies.

As it flows through the receiver/drier (3) the refrigerant is purified of all chemical and mechanical impurities.

The liquid refrigerant then flows through the expansion valve (4) into the evaporator (5), located in the fresh air flow. The refrigerant evaporates here. The evaporation process absorbs heat from the fresh air flowing by on the outside of the system of tubes and honeycombs so that they cool the fresh air.

On vehicles with rear air conditioning the liquid refrigerant flows from the receiver/drier (3) through the refrigerant injection valve (8) and the refrigerant shutoff valve (7) into the rear air conditioning evaporator (6).

The moisture contained in the air is condensed out and the water condensate is drained to the outside. The air is dried.

The A/C compressor (1) sucks in the refrigerant which has now become gaseous due to the heat it has absorbed and compresses it again.

When the engine is running and blower switched on cool air can be let into the interior via various outlets. The intensity of the refrigeration depends on the interior temperature and blower speed set previously.

Refrigerant circuit, function - GF83.40-P-2001N

MODEL 215

Identifying Rear A/C Pushbutton Control Module And Air Distribution Controller. Scheme 124

The A/C compressor (1) is driven by the engine and compresses the gaseous refrigerant which heats up, flows to the condenser (2) where it is cooled down. The heat from compression is removed from the refrigerant by the surface of the condenser (2). As it cools the refrigerant liquefies.

As it flows through the receiver/drier (3) the refrigerant is purified of all chemical and mechanical impurities.

The liquid refrigerant then flows through the expansion valve (4) into the evaporator (5), located in the fresh air flow. The refrigerant evaporates here. The evaporation process absorbs heat from the fresh air flowing by on the outside of the system of tubes and honeycombs so that they cool the fresh air.

The moisture contained in the air is condensed out and the water condensate is drained to the outside. The air is dried. The A/C compressor (1) sucks in the refrigerant which has now become gaseous due to the heat it has absorbed and compresses it again.

When the engine is running and the blower switched on cool air can be let into the interior via various outlets. The intensity of the refrigeration depends on the interior temperature and blower speed set previously.

Automatic air conditioning control, function - GF83.40-P-2004I

MODEL 220

Automatic Air Conditioning Control Function Diagram - Model 220. Scheme 125

Function

All control modules with a control function for the automatic air conditioning are connected with one another by the passenger compartment bus (CAN class B). The CAN data bus is a bidirectional bus, i.e. each control module connected is capable of transmitting and receiving information.

A defined data protocol specifies how and when the control modules can transmit and receive information. The CAN data bus has a message-related address system.

This means that each message is assigned a fixed address (identifier), indicating the contents of the message. The receiver evaluates only the messages (data telegrams) stored in its list of messages to be received (acceptancy check).

Communication for temperature control between automatic A/C pushbutton control module and rear A/C pushbutton control module

The automatic A/C pushbutton control module reads all values set on the rear A/C pushbutton control module in the passenger compartment bus (CAN class B) and calculates internally the required outlet temperatures for the entire passenger compartment. The values calculated for the left and right rear are transferred to the rear A/C pushbutton control module via the passenger compartment bus (CAN class B). The rear A/C pushbutton control module regulates its outlet temperatures itself.

Automatic air conditioning control, function - GF83.40-P-2004N

MODEL 215

Function

All control modules with a control function for the automatic air conditioning are connected with one another by the passenger compartment bus (CAN class B). The CAN data bus is a bidirectional bus, i.e. each control module connected is capable of transmitting and receiving information.

A defined data protocol specifies how and when the control modules can transmit and receive information.

The CAN data bus has a message-related address system. This means that each message is assigned a fixed address (identifier), indicating the contents of the message. The receiver evaluates only the messages (data telegrams) stored in its list of messages to be received (acceptancy check).

Blower button, function - GF83.40-P-2100-01I

The blower button ( ) switches a control voltage of 0 - 6 V to the blower regulator via the automatic A/C pushbutton control module

There are seven set manual positions, adjustable by increasing or decreasing with the blower button. This allows control of the blower speed between 0 - 100 %. The automatic blower function can be adjusted by pressing the blower button or arresting one of the two AUTO buttons for the blower control.

Recirculated air button, function - GF83.40-P-2102-01I

Function

The fresh air/recirculated air flap actuator motor can be controlled by momentarily pressing the recirculated air button

( , < 1.5 s). This causes the fresh air flap to close and recirculated air flap to open to prevent air from coming from the outside. The LED function indicator comes on in the recirculated air mode

Recirculated air convenience feature

If the recirculated air button ( ) or activated charcoal filter button ( ) is pressed > 1.5 s, all open windows and the sliding/ pop-up roof are closed automatically in addition to starting the recirculated air function (windows and sliding/pop-up roof must have been synchronized previously). The LED function indicator comes on during the recirculated air mode. The sliding/pop-up roof and power windows are closed one after another to avoid excessively high currents

When the button is pressed again for longer than 1.5 s, the windows and sliding/pop-up roof moves back to the previously stored position and the fresh air/recirculated air flap moves to the fresh air position (LED off). This convenience function can only be started when the recirculated air indicator LED or activated charcoal filter indicator LED are not burning.

Any window opened manually during this recirculated air phase remains in this position when the recirculated air function is canceled, all other windows move back to the stored position. The position of the sliding/pop-up roof and side windows before starting the closing operation are stored by the overhead control panel control module or the corresponding door control module. The windows and sliding/pop-up roof closed with this convenience feature remain closed if the recirculated air button is pressed only momentary (t < 1.5s). In this case only the fresh air/recirculated air flap is moved to the fresh air position. The stored positions are deleted when the ignition is switched off.

Recirculating air pushbutton, function - GF83.40-P-2102-01N

Function

Pressing (t<1.5 sec.) the recirculating air pushbutton ( ) actuates the fresh air/recirculation door actuator motor, which closes the fresh air flap and opens the recirculation door in order to prevent air from entering from the outside. The LED function illuminates while the recirculating air system operates

Convenience recirculated air function as of 01.06.01

If the recirculating air pushbutton ( ) is held down, in addition to activating the recirculating air function all open windows and the sliding/tilting roof are closed (windows and sliding/tilting roof must be normalized). The LED function illuminates while recirculating air system operates. In order to avoid current spikes the sliding/tilting roof and the power windows are actuated in sequence

If the button is held down again, the windows and the sliding/tilting roof move back to their previously stored positions and the fresh air/ recirculation door returns to the fresh air position (LED off). The convenience function can only be operated if the recirculated air LED if off.

Any window that was manually opened during this recirculating air phase remains in this position when the recirculating air function is disabled, and all others move to their stored positions. The positions of the sliding/tilting window and the side windows prior to the closing procedure are stored by the overhead control panel control module or the relevant door control module. The windows and the sliding/tilting roof that were closed by the convenience function remain closed if the recirculating air pushbutton is operated, even briefly (t<1.5 sec.). Only the fresh air/recirculation door is moved to the fresh air position in this case. The saved positions are erased if the ignition is switched off.

EC button, function - GF83.40-P-2103-01I

Function

When the EC button ( ) on the automatic air conditioning pushbutton control module is pressed an LED comes on, the refrigerant compressor is switched off and cooling operation is therefore switched off. The air is no longer cooled and dried. All other functions are retained

The pollutant-controlled recirculated air function is not available in EC mode.

In order to switch the refrigerant compressor off, the automatic air conditioning sends the switch-off request and a specified value = 0 % to the left SAM via the CAN bus. At the same time, the refrigerant compressor torque is set to "0" and transferred to the engine electronics and the electronic transmission control via the electronic ignition lock control module. The left SAM sends the canceled load increase signal to the engine electronics via the electronic ignition lock control module and switches the refrigerant compressor off after a defined time delay (approx. t = 450 ms).

Automatic air conditioning housing, function - GF83.40-P-2105-02I

Automatic air conditioning heating mode (AAC)

Automatic air conditioning heating mode (AAC)

Settings

1. EC OFF
2. both AUTO buttons engaged OFF OFF OFF
3. Center outlet on AUTO

Function

In heating mode, fresh air (A) is drawn in by the blower (21) via the fresh air flap (1) or in recirculated air mode, interior air is drawn in via the air recirculation flap (2). The air cleaned by the dust filter (20) is led past the two activated charcoal filters (22) (activated charcoal filters not switched on) and flows through the cooled evaporator (23) and is dried and cooled down there. Then the dried and cooled air (B) is heated up again in the heated heater heat exchanger (24). The heated air (C) is led to the air outlets (7, 8, 9, 10 and 11)

Footwell OPEN

Defroster outlets restricted other flap can be operated manually

The center outlet diverter flaps (4) are closed in heating mode. In this function the defroster outlets (7a) are open slightly. In the transition from heating mode to cooling mode (mode change) the footwell flaps (11) start to close and the center outlet blend flap (5) starts to open. The condensation water is led off into the atmosphere via the condensation water drain (25).

Automatic air conditioning (AAC) cooling mode, interior heated up

Automatic air conditioning cooling mode (AAC)

Settings

1. EC OFF
2. both AUTO buttons engaged OFF OFF OFF
3. Center outlet on AUTO

Function

In cooling mode, fresh air (A) is drawn in by the blower (21) via the fresh air flap (1) or in recirculated air mode, interior air is drawn in via the air recirculation flap (2). The air cleaned by the dust filter (20) is led past the two activated charcoal filters (22) (activated charcoal filters not switched on) and flows through the cooled evaporator (23) and is dried and cooled down there. Then the dried and cooled air (B) is led through the unheated heater heat exchanger (24) to the air outlets (7,8,9 and 10). The dried and cooled air is led to the center outlet (6) via the open center outlet blend flaps (5). The center outlet diverter flaps (4) can also be opened if it is necessary to cool down the interior very rapidly. When the interior temperature approaches the preselected interior temperature, the center outlet diverter flaps (4) close again slowly. The center outlet diverter flaps (4) are closed in the regulated condition.

The footwell flaps (11) are closed in cooling mode.

The defroster outlet flaps (7) can be opened when the outside air is dry. Other flaps can be operated manually. During the transition from cooling mode to heating mode (mode change) the center outlet blend flaps (5) start to close and the footwell flaps (11) start to open. The condensation water is led off into the atmosphere via the condensation water drain (25).

Automatic air conditioning normal mode (AAC), EC illuminated --> no heating mode

Identifying Automatic Air Conditioning Normal Mode (AAC), EC Illuminated --> No Heating Mode. Scheme 126

Automatic air conditioning (AAC) normal mode

Settings

1. EC OFF
2. both AUTO buttons engaged OFF OFF OFF
3. Center outlet on AUTO

Function

In normal mode, (EC illuminated), fresh air (A) is drawn in by the blower (21) via the fresh air flap (1) or in recirculation mode, interior air is drawn in via the air recirculation flap (2). The air cleaned (A) by the dust filter (20) is led past the two activated charcoal filters (22) (activated charcoal filters not switched on) and flows through the uncooled evaporator (23). Then the air (A) is led through the unheated heater heat exchanger (24) to the air outlets (7, 8, 9, and 11). The air (A) is led to the center outlet (6) via the opened center outlet blend flaps (5) and center outlet diverter flaps (4).

The defroster outlet flaps (7) can be opened when the outside air is dry. Other flaps can be operated manually.

Automatic air conditioning (AAC), heating mode with activated charcoal filter

EC not illuminated

Identifying Rear Air Conditioning Box Components Location/Design. Scheme 127

Automatic air conditioning (AAC), heating mode with activated charcoal filter

Settings

1. EC OFF
2. both AUTO buttons engaged ON OFF OFF
3. Center outlet on AUTO

Function

In heating mode, fresh air (A) is drawn in by the blower (21) via the fresh air flap (1) or in recirculated air mode, interior air is drawn in via the air recirculation flap (2). The air cleaned by the dust filter (20) is led through the two activated charcoal filters (22) ( , LED illuminated) and flows through the cooled evaporator (23) and is dried and cooled down there. Then the dried and cooled air (B) is heated up again in the heated heater heat exchanger (24). The heated air (C) is led to the air outlets (7, 8, 9, 10 and 11)

Footwell OPEN

Defroster outlets restricted

other flap can be operated manually

The center outlet diverter flaps (4) are closed in heating mode. In this function the defroster outlets (7a) are open slightly. In the transition from heating mode to cooling mode (mode change) the footwell flaps (11) start to close and the center outlet blend flap (5) starts to open. The condensation water is led off into the atmosphere via the condensation water drain (25).

Automatic air conditioning (AAC), cooling mode with activated charcoal filter

EC not illuminated

Identifying A/C Compressor Components. Scheme 128

Automatic air conditioning (AAC) cooling mode with activated charcoal filter

Settings

1. EC OFF
2. both AUTO buttons engaged ON OFF OFF
3. Center outlet on AUTO

Function

In cooling mode, fresh air (A) is drawn in by the blower (21) via the fresh air flap (1) or in recirculated air mode, interior air is drawn in via the air recirculation flap (2). The air cleaned by the dust filter (20) is led through the two activated charcoal filters (22) ( , LED illuminated) and flows through the cooled evaporator (23) and is dried and cooled down there

Then the dried and cooled air (B) is led through the unheated heater heat exchanger (24) to the air outlets (7, 8, 9, and 10). The dried and cooled air is led to the center outlet (6) via the open center outlet blend flaps (5). The center outlet diverter flaps (4) can also be opened if it is necessary to cool down the interior very rapidly. When the interior temperature approaches the preselected interior temperature the center outlet diverter flaps (4) close again slowly. The center outlet diverter flaps (4) are closed in the regulated condition.

The footwell flaps (11) are closed in cooling mode.

The defroster outlet flaps (7) can be opened when the outside air is dry. Other flaps can be operated manually. During the transition from cooling mode to heating mode (mode change) the center outlet blend flaps (5) start to close and the footwell flaps (11) start to open. The condensation water is led off into the atmosphere via the condensation water drain (25).

Automatic air conditioning housing, purpose - GF83.40-P-2105-03I

The automatic air conditioning housing serves to hold the following components

1. Air guide flaps (1 to 11)
2. Dust filter (20)
3. Blower with blower control (21)
4. Activated charcoal filter (22)
5. Evaporator (23)
6. Heater core (24)
7. Expansion valve
8. Actuator motors

forming one complete unit.

The automatic air conditioning housing serves for distribution of the air required for ventilation of the vehicle to the appropriate air ducts and air outlets depending on the desired temperature in the passenger compartment.

The air guidance is dependent on various operating states such as

Scheme 129

1. Heater mode
2. Cooling mode
3. Normal operation
4. Heater operation with activated charcoal filter
5. Cooling mode with activated charcoal filter see scheme 84: Identifying Automatic Air Conditioning Housing Function

AC OFF button function - GF83.40-P-2107-01IA

Function

When the AC OFF button ( ) on the automatic air conditioning pushbutton control module is pressed an LED comes on, the refrigerant compressor is switched off and cooling operation therefore switched off. The air is no longer cooled and dried. All other functions are retained

The pollutant-triggered recirculating air function is not available in AC OFF mode.

In order to switch the refrigerant compressor off, the automatic air conditioning sends the switch-off request and a specified value = 0 % to the left SAM via the CAN bus. At the same time, the refrigerant compressor torque is set to "0" and transferred to the engine electronics and the electronic transmission control via the electronic ignition lock control module. The left SAM sends the canceled load increase signal to the engine electronics via the electronic ignition lock control module and switches the refrigerant compressor off after a defined time delay (approx. t = 450 ms).

REST button, function - GF83.40-P-2109-01I

Function

The residual engine heat utilization system can be switched on by pressing the REST button ( ) on the automatic A/C pushbutton control module ("REST" appears on display)

When the engine is switched off the residual heat is used to heat the passenger compartment depending on the temperature set on the automatic A/C pushbutton control module and the ambient temperature.

Heating is possible for approx. 30 minutes after shutting off the engine. This function is possible only with the ignition switched off or with the ignition lock in position 1. If the voltage is too low the residual engine heat utilization feature is switched off automatically. The flaps are in the automatic mode and the air quantity is also adjusted automatically.

The residual engine heat utilization function is switched off

1. When the electronic key is turned to position 2 in the ignition switch.
2. After approx. 30 minutes or after approx. 15 minutes when the REST feature is activated simultaneously on the rear air conditioning.
3. When the battery voltage decreases.

REST button, function - GF83.40-P-2109-01N

Function

The residual engine heat utilization system can be switched on by pressing the REST button ( ) on the automatic A/C pushbutton control module ("REST" appears on display)

When the engine is switched off the residual heat is used to heat the passenger compartment depending on the temperature set on the automatic A/C pushbutton control module and the ambient temperature.

Heating is possible for approx. 30 minutes after shutting off the engine. This function is possible only with the ignition switched off or with the ignition lock in position 1. If the voltage is too low the residual engine heat utilization feature is switched off automatically. The flaps are in the automatic mode and the air quantity is also adjusted automatically.

The residual engine heat utilization function is switched off

1. When the electronic key is turned to position 2 in the ignition switch.
2. After approx. 30 minutes.
3. When the battery voltage decreases.

Display, function - GF83.40-P-2114-01I

Function

The display serves primarily for indicating to the driver the ventilation and air conditioning settings. This information is provided in the form of words, symbols and numbers.

The temperature is displayed either in °C or in °F depending on the setting on the multifunction steering wheel. Otherwise messages are indicated with corresponding symbols.

The display is operated as a positive or negative display depending on the ambient brightness. All displays in the vehicle are switched over simultaneously for this purpose by a central light junction point in the overhead control panel control module.

1. Positive display (bright surrounding): black numbers on light background
2. Negative display (dark surrounding): light numbers on dark background

Electric engine/air conditioning fan function - GF83.40-P-2118-01I

Function

The power of the electric engine/air conditioning fan is controlled by the engine electronics (infinitely variable).

The automatic air conditioning pushbutton control module calculates the fan speed setting depending on the refrigerant pressure and transmits the request to the engine electronics via the electronic ignition lock control module.

In air conditioning mode with an outside temperature of 15 °C and ground speed of below 70 km/h, a basic ventilation capacity of 40 % is requested.

The engine electronics calculate the fan speed setting depending on the engine temperature and compare this with the request from the air conditioning. The greater of the two is output as the control signal.

Electric engine/air conditioning fan function - GF83.40-P-2118-01IA

Function

The power of the electric engine/air conditioning fan is controlled by the engine electronics (infinitely variable).

The electronic ignition lock pushbutton control module calculates the fan speed setting depending on the refrigerant pressure and transmits the request to the engine electronics. The refrigerant pressure value is received by the electronic ignition switch control module via the automatic air conditioning pushbutton control module.

In air conditioning mode with an outside temperature of 15 °C and ground speed of below 70 km/h a basic ventilation capacity of 40 % is requested.

The engine electronics calculate the fan speed setting depending on the engine temperature and compare this with the request from the air conditioning. The greater of the two is output as the control signal.

Condenser, function - GF83.40-P-2120-01I

Function

The hot refrigerant coming from the A/C compressor is pressed into the condenser from the top. Banks of tubes and louvers quickly absorb this heat. Outside air is pressed or pulled through the condenser, heats up cooling thereby the refrigerant.

As the refrigerant cools down to a certain temperature depending on the pressure, it condenses and liquefies. The liquid refrigerant then flows out at the bottom of the condenser to the receiver/drier.

Evaporator, function - GF83.40-P-2121-01I

Function

The liquid refrigerant is injected into the evaporator at high pressure. The heat required for evaporation is taken from the air flowing past the evaporator which is thereby cooled. The soldered half-discs with fins provide a large evaporator surface to ensure rapid heat exchange.

The air humidity which condenses out of the air is drained to the outside through water condensate drain hoses. In addition solid particles in the air are bound by the condensing water thereby purifying the air.

Receiver/drier, function - GF83.40-P-2122-01I

Function

The liquid refrigerant flows under pressure through the receiver/drier, where it flows through a stainless steel mat to the filter block. The filter block can absorb a small quantity of water. The pores in the filter block are matched precisely to the molecular size of the refrigerant. This allows the refrigerant to flow through the filter block.

All other substances are held back and stored by this molecular sieve. The purified refrigerant then flows through a riser pipe to the expansion valve.

Expansion valve function - GF83.40-P-2123-01I

Function

When the A/C compressor switches on the pressure in the evaporator decreases causing the diaphragm (1) to arch downward. The tappet (3) follows the motion of the diaphragm and presses the valve ball (4) away from its seat against the force of the spring (5). The refrigerant is sprayed into the evaporator through the open valve.

Since the motion of the diaphragm depends on the intake pressure as well as the temperature at the evaporator outlet, only the amount of refrigerant is injected that can be evaporated optimally.

Identifying Outside Air Temperature Sensor. Scheme 130

Refrigerant temperature sensor, function - GF83.40-P-2124-01I

Function

The refrigerant temperature sensor measures the temperature of the refrigerant and transfers the value measured to the automatic A/C pushbutton control module via the left signal-acquisition and actuation module and the CAN bus. This value is compared with a stored temperature/pressure curve allowing the refrigerant level to be determined. If the refrigerant level is too low the A/C compressor is switched off by the pushbutton control module via the CAN bus and left signal-acquisition and actuation module.

The EC mode is activated and can no longer be switched off. The system is capable of operating again only after elimination of the malfunction and erasing the DTC memory in the automatic A/C pushbutton control module. The refrigerant temperature sensor operates within the range of -40 °C to +100 °C.

Climate control coolant temperature sensor, function - GF83.40-P-2125-01I

Function

The climate control coolant temperature sensor measures the temperature of the coolant and transfers the value measured to the automatic A/C pushbutton control module via the electronic ignition/ starter switch control module and CAN bus. At a coolant temperature of 190°C to 127 °C the A/C compressor output is reduced linearly, at a temperature above 127 °C the A/C compressor is switched off by the pushbutton control module via the CAN bus and the left signal-acquisition and actuation module. The coolant temperature sensor operates within the range of -40°C to +214°C.

Refrigerant pressure sensor, function - GF83.40-P-2126-01I

Function

The refrigerant pressure sensor measures the refrigerant pressure and transfers the value measured to the automatic A/C pushbutton control module via the left signal-acquisition and actuation module and the CAN bus. This value is compared with a stored temperature/ pressure curve. The refrigerant pressure sensor operates within the range of 0 to 35 bar.

Switching off the A/C compressor

The A/C compressor is switched off at the following values.

1. Refrigerant pressure < 1.75 bar = A/C compressor off
2. Refrigerant pressure > 30 bar = A/C compressor off

Switching on the electric engine/A/C electric fan

The engine/A/C electric fan is switched on at the following values

1. Refrigerant pressure < 12 bar = fan off
2. Refrigerant pressure > 20 bar = fan on (100%)
3. Refrigerant pressure 12 bar to 20 bar = Infinite linear increase in fan speed (40-100%)

Defroster button, function - GF83.40-P-2139-02I

Function

The defroster function is started when the defroster button ( ) is pressed. The temperature is set to maximum and the air flow is distributed to the defroster and side nozzles. All other flaps are closed. The blower voltage is regulated depending on the coolant temperature. The symbol "DEFROST" appears on the display in the automatic A/C pushbutton control module

The "DEFROST" symbol also appears on the display in the rear A/C pushbutton control module, however, the heat exits only at the windshield at the front.

Defroster button, function - GF83.40-P-2139-02N

Function

The defroster function is started when the defroster button ( ) is pressed. The temperature is set to maximum and the air flow is distributed to the defroster and side nozzles. All other flaps are closed. The blower voltage is regulated depending on the coolant temperature. The symbol "DEFROST" appears on the display in the automatic A/C pushbutton control module

Temperature button, function - GF83.40-P-2141-02I

Function

The desired interior temperature can be set separately for the left and right with the temperature button ( ) on the automatic A/C pushbutton control module. The automatic A/C pushbutton control module compares the set temperature with the temperature in the vehicle passenger compartment measured by the two in-car temperature sensors. The automatic A/C pushbutton control module uses the difference between the actual and set values to calculate the opening time for the duovalves and actuates them separately for the left the right side. When it is necessary to heat up or cool down the passenger compartment the set temperature is reached as quickly as possible and held constant

Center vent electronics control module task - GF83.40-P-2142-02I

Task

The position of the 3 selectors and the automatic detent position at the center outlet are read in by the center outlet electronics control module and conveyed to the AAC pushbutton control module via the air conditioning bus. The quantity of air and air temperature from the center outlet are controlled and regulated based on this data.

In automatic mode the function of the center outlet is designed so that the interior temperature desired by the operator is reached as quickly as possible and maintained. This control takes place under comfortable conditions for the occupants.

Blend flaps OPEN = Air downstream of heat exchanger to center outlet

Diverter flaps OPEN = Air direct from evaporator to center outlet

Stepping motor electronic control module, purpose - GF83.40-P-2143-02I

Purpose

The 10 actuator motors on the A/C housing are controlled by the stepping motor electronic control module. The switching logic is realized by the automatic A/C pushbutton control module.

The flap settings are adjusted infinitely from 0 % (closed) to 100% (open) by the stepping motor electronic control module according to the position settings received from the automatic A/C pushbutton control module via the A/C bus.

The electronic flap control completes all adjustments with a resolution of 1 %. It is necessary to realize the following LOOSE function for each flap in the automatic A/C pushbutton control module so that the actuator motors do not run continuously within the control range.

LOOSE-function: Once a position is reached, it is necessary for the air outlet temperature at the center vent to change to such an extent that the next higher or lower LOOSE value is exceeded or left below before the position is changed again

End values (0%; 100%) are moved to directly.

Ignition off

The actuation motors move to the following positions one minute after switching off the ignition

1. Footwell flaps 0% (without rear air conditioning) 100% (with rear air conditioning)
2. Defroster flaps 0%
3. All other flaps remain in the last set position

Ignition on

The following positions apply for the first 30 seconds after switching on the ignition

1. Footwell flaps 0% (without rear air conditioning) 100% (with rear air conditioning)
2. Defroster flaps 0%
3. Blend flaps depending on exit temperature of air or manual setting on center vent
4. Diverter flaps automatically depending on air exit temperature or manual setting on center vent
5. Thereafter the automatic flap states for manual settings apply

Exceptions

1. Cold start inhibit: the defroster nozzles must open immediately when the outdoor temperature is < -5°C and simultaneously the coolant temperature < 40 °C when the ignition is switched ON.
2. Unit in A/C mode: footwell must close immediately after switching ignition on
3. Defrost program: logic lock-up, electronic nozzles must open immediately and footwell must close immediately when ignition is switched on.

Mode change to automatic flap operation

Generally there is a so-called mode change-over range for all flaps at the transition from the heating mode to the A/C-mode and vice versa.

Setting deviation < -4 °C

1. Footwell flaps 0% (without rear air conditioning) 100% (with rear air conditioning)
2. Defroster flaps 40%
3. Blend flaps 0%

Setting deviation > -4 °C

1. Footwell flaps 50%
2. Defroster flaps 0%
3. Blend flaps 100%
4. Diverter flaps depending on outside temperature

Note. Manual air distribution (also recirculated air switchover), fixed programs have priority over the flap positions specified above. In the same manner a manual setting on the center vent has priority over the blend and diverter flap values in the table above

Stepping motor electronics control module, purpose - GF83.40-P-2143-02N

Purpose

The 10 actuator motors on the A/C housing are controlled by the stepping motor electronics control module. The switching logic is realized by the automatic A/C pushbutton control module.

The flap settings are adjusted infinitely from 0 % (closed) to 100% (open) by the stepping motor electronics control module according to the position settings received from the automatic A/C pushbutton control module via the A/C bus.

The electronic flap control completes all adjustments with a resolution of 1 %. It is necessary to realize the following LOSE function for each flap in the automatic A/C pushbutton control module so that the actuator motors do not run continuously within the control range.

LOSE-function: Once a position is reached, it is necessary for the air outlet temperature at the center vent to change to such an extent that the next higher or lower LOSE value is exceeded or left below before the position is changed again

End values (0%; 100%) are moved to directly.

Ignition OFF

The actuator motors move to the following positions one minute after switching off the ignition

1. Footwell flaps 0%
2. Defroster flaps 0%
3. All other flaps remain in the last set position

Ignition ON

The following positions apply for the first 30 seconds after switching on the ignition

1. Footwell flaps 0%
2. Defroster flaps 0%
3. Blend flaps depending on exit temperature of air or manual setting on center vent
4. Diverter flaps automatically depending on air exit temperature or manual setting on center vent
5. Thereafter the automatic flap states for manual settings apply

Exceptions

1. Cold start inhibit: the defroster nozzles must open immediately when the outdoor temperature is < -5°C and simultaneously the coolant temperature < 40 °C when the ignition is switched ON.
2. Unit in A/C mode: footwell must close immediately after switching ignition on
3. Defrost program: logic lock-up, electronic nozzles must open immediately and footwell must close immediately when ignition is switched on.

Mode change to automatic flap operation

Generally there is a so-called mode change-over range for all flaps at the transition from the heating mode to the A/C-mode and vice versa.

Setting deviation < -4 °C

1. Footwell flaps 0%
2. Defroster flaps 40%
3. Blend flaps 0%

Setting deviation > -4 °C

1. Footwell flaps 50%
2. Defroster flaps 0%
3. Blend flaps 100%
4. Diverter flaps depending on outside temperature

Note. Manual air distribution (also recirculated air switchover), fixed programs have priority over the flap positions specified above. In the same manner a manual setting on the center vent has priority over the blend and diverter flap values in the table above.

Rear air conditioning pushbutton control module function - GF83.50-P-2000M

MODEL 220 with CODE (582) rear air conditioning

Function

The rear air conditioning pushbutton control module (N22/3) allows the temperature to be individually adjusted for passengers in the rear

1. The blow-out temperature in the rear is controlled by pressing the left and right temperature buttons ( )
2. Manual/automatic air quantity by pressing the blower button ( )
3. Manual air distribution duct from the rear nozzle between the front seats or the rear footwell nozzle by adjusting the air distribution regulator (1)
4. Activating the residual engine heat utilization system with the ignition switched off by pressing the REST button ( )
5. Switch ON/OFFby pressing the ON/OFF button ( )

The control module integrated in the rear air conditioning pushbutton control module (N22/3) still directly regulates the following components

1. Rear duo valves
2. Rear heating water circulation pump
3. Rear blower regulator
4. Rear air distribution valve actuator motor
5. Refrigerant shut-off valve

The following sensor signals are directly read in by the rear air conditioning pushbutton control module (N22/3)

1. Left and right rear heat exchanger temperature sensor
2. Evaporator temperature sensor

Communication between the automatic air conditioning pushbutton control module and the rear air conditioning pushbutton control module.

1. Temperature control: The automatic air conditioning pushbutton control module reads in all the rear air conditioning pushbutton control module set points and internally calculates the required blow-in temperatures for the entire interior. The values calculated for the rear left and right are sent to the rear air conditioning pushbutton control module, which regulates the blow-in temperatures itself. If the rear seats are unoccupied (detected via buckle), the temperature control is automatically set to 22 °C. As of 01.06.01 the temperature control will be taken over from the automatic air conditioning pushbutton control module if the rear seats are unoccupied.
2. Blower control: If the rear air conditioning pushbutton control module is in automatic blower mode, the front blower level is taken over. As of 01.06.01 the blower control in automatic blower mode will be directly controlled by the rear air conditioning pushbutton control module.
3. Remote control of rear air conditioning pushbutton control module by automatic air conditioning pushbutton control module: If the blower button on the automatic air conditioning pushbutton control module is held down in the AUTO position for approx. 1 second, a control module symbol appears in the front display together with the rear air conditioning settings. These settings can then be modified from the front. The rear air conditioning can also be switched off using the ON/OFF button ( ). The function is automatically exited if no adjustments are made for 3 seconds.

Rear air conditioning air distribution flap actuator motor, function - GF83.50-P-2100-02M

Function

The rear air conditioning air distribution flap actuator motor is controlled directly by the rear A/C pushbutton control module proportionally to the setting on the selection dial and actuates the rear air distribution flap.

Rear air conditioning air distribution control, function - GF83.50-P-2101-02M

Function

The rear air conditioning air distribution control in the rear A/C pushbutton control module controls the air distribution flap actuator motor for air distribution to the rear nozzle or rear footwell nozzle infinitely proportional to the position of the air distribution control. The air distribution flap actuator motor is controlled directly by the rear A/C pushbutton control module.

Rear air conditioning box function - GF83.50-P-2102-02M

Rear air conditioning normal mode

Scheme 131

Rear air conditioning normal mode

Function

In normal mode, recirculated air (A) is drawn out of the vehicle interior by the blower (1) when the rear air conditioning is switched off. The recirculated air (A) flows through the uncooled evaporator (2). Then the recirculated air (A) is led through the unheated heater heat exchanger (3) and, depending on the position of the air distribution flap (5), to the air outlets (4 and 6).

Rear air conditioning cooling mode

Identifying Rear Air Conditioning Cooling Mode. Scheme 132

Rear air conditioning cooling mode

Function

In cooling mode, recirculated air (A) is drawn out of the vehicle interior by the blower (1) when the rear air conditioning is switched on. The recirculated air (A) flows through the cooled evaporator (2) and is cooled down. Then the dried and cooled air (B) is led through the unheated heater heat exchanger (3) and, depending on the position of the air distribution flap (5), to the air outlets (4, 6).

If the rear footwell cooling is adjusted via the rear air conditioning air distribution regulator, the footwell flaps for the rear footwell on the front automatic air conditioning box are closed automatically.

The condensation water is led off into the atmosphere via the condensation water drain (7).

Rear air conditioning heating mode

Scheme 133

Rear air conditioning heating mode

Function

In heating mode, recirculated air (A) is drawn out of the vehicle interior by the blower (1) when the rear air conditioning is switched on. The recirculated air (A) flows through the cooled evaporator (2) and is cooled down there. Then the dried and cooled air (B) is heated up through the heated heater heat exchanger (3). The heated air (C) is led to the air outlets (4, 6) depending on the position of the air distribution flap (5).

The condensation water is led off into the atmosphere via the condensation water drain (7).

Rear air conditioning housing, purpose - GF83.50-P-2102-03M

Purpose

The rear A/C housing serves for holding the following components

1. Blower (1)
2. Evaporator (2)
3. Heater core (3)
4. Air distribution flap (5)
5. Air distribution flap actuator motor

and thereby forms one complete unit.

The rear A/C housing provides for distribution of the air required for ventilation of the rear passenger compartment to the air outlets depending on the desired temperature in the rear passenger compartment.

The air distribution depends on various operating states such as

Scheme 134

1. Normal operation
2. A/C operation
3. Heater operation see scheme 113: Identifying Rear Air Conditioning Housing Function

Rear air conditioning refrigerant shutoff valve, function - GF83.50-P-2103-02M

Function

The rear A/C refrigerant shutoff valve is controlled directly by the rear A/C pushbutton control module and shuts off the rear refrigerant circuit under the following conditions

1. ON/OFF button ( )actuated
2. Rest button ( )actuated
3. Signal from evaporator temperature sensor to rear A/C pushbutton control module (evaporator iced up)

Rear air conditioning blower button function - GF83.50-P-2105-02M

Function

The blower button ( ) uses the rear air conditioning pushbutton control module to switch a control voltage of 0 - 6 V to the rear blower regulator

7 manual fixed stages can be engaged using the blower button. This facilitates blower speed control of 0 -100%.

Automatic blower function settings are made by adjusting the vertical position of the blower button ( )

In automatic operation, the control voltage for the rear blower regulator is calculated using the automatic air conditioning control voltage read in from the CAN BUS.

as of 01.06.01

In automatic operation, the control voltage for the rear blower regulator is calculated directly by the rear air conditioning pushbutton control module.

Rear air conditioning temperature button, function - GF83.50-P-2106-02M

Function

The desired rear passenger compartment temperatures can be set separately for the left and right by pressing the temperature buttons ( ) on the rear A/C pushbutton control module. The rear A/C pushbutton control module compares the set temperatures with the temperature present in the vehicle passenger compartment measured by the two in-car temperature sensors. The rear A/C pushbutton control module calculates the opening time for the duovalves and actuates them separately for the left and right sides by comparing the actual values and set values and actuates the duovalves separately for the left and right sides. When it is necessary to heat up or cool down the passenger compartment the set temperature is reached as quickly as possible and held constant

Rear air conditioning REST button, function - GF83.50-P-2107-02M

Function

The residual engine heat utilization function can be switched on by pressing the REST button ( ) on the rear A/C pushbutton control module (word "REST" appears on display). When the engine is shut off the residual heat is used to heat the car depending on the temperature set on the rear A/C pushbutton control module and the ambient temperature in the vehicle passenger compartment. The car can continue to be heated for approx. 30 minutes after shutting off the engine. This function is possible only with the ignition switched off or with the ignition lock in position 1. The residual heat function is switched off automatically when the battery voltage is low

Automatic switch-off is accomplished

1. When the electronic key in the ignition switch is turned to position 2.
2. After approx. 30 minutes or after approx. 15 minutes when the residual engine heat function is activated simultaneously on the automatic A/C (retriggering is possible).
3. When the battery voltage drops.

Rear air conditioning display, function - GF83.50-P-2109-02M

Function

The display serves primarily for indicating to the vehicle passengers the settings for the ventilation and air conditioning. This information is displayed in words, symbols and numbers.

The temperature is indicated either in °C or °F depending on the setting on the multifunction steering wheel. Other messages are displayed with the corresponding symbols.

The display is either positive or negative depending on the ambient brightness. All vehicle displays are switched over simultaneously and centrally by the light junction point in the overhead control panel control module.

1. Positive display (bright surroundings): black characters on light background.
2. Negative display (dark surroundings): light characters on dark background.

Rear air conditioning evaporator, function - GF83.50-P-2111-02M

Function

The liquid refrigerant is injected into the rear evaporator under high pressure.

The heat required for evaporation is taken from the air flowing past the evaporator which is cooled down. The fins and louvers provide the evaporator with a large surface to ensure quick exchange of the heat.

The moisture in the air which condenses out as the air cools is drained to the outside by water condense drain hoses. In addition solid particles in the air are bound by the water as it condenses thereby purifying the air.

Pulley, function - GF83.55-P-2103-02I

Function during normal operation

During normal operation the rubber element (2) is resistant to deformation. The rubber element (2) therefore transfers the torque from the pulley (3) to the hub (1) and simultaneously to the A/C compressor shaft, whereby the hub (1) and pulley (3) turn in the direction indicated by the arrow. In this operating state the following torque relationship exists

A/C compressor torque < rubber element torque limit

In this operation state the rubber element (2) operates as a damping element by preventing resonance with other engine components over the pulley.

Scheme 135

Function when A/C compressor locks up

When the A/C compressor locks up the torque required to drive the A/C compressor is greater than the torque present at the pulley (3). This causes slip between the pulley (3) and hub (1) resulting from the change in shape and wear to the rubber element (2). The pulley (3) continues to turn even though the A/C compressor is locked up. In this operating state the following torque relationship exists

A/C compressor torque > rubber element torque limit

In this operation state the rubber element (2) acts as a belt protection device.

Scheme 136

Pressure relief valve, function - GF83.55-P-2104-02I

Function

The pressure relief valve is designed as a pressure dependent wax valve. It begins to act if all other pressure-dependent safety devices can no longer prevent a pressure increase in the A/C compressor. The wax withstands a pressure of < 35 bar. If the pressure increases to a value above 35 bar, the wax is destroyed and the pressure is released to the resulting opening.

Temperature control function - GF83.57-P-2000I

MODEL 220

Identifying Temperature Control Interlinkage Components. Scheme 137

Function

The electronically controlled cooling, heating and ventilation part of the automatic air conditioning and rear compartment air conditioning reaches or maintains constant the required interior temperature in the fastest possible time by

1. Cooling of the air by means of the evaporator
2. Heating up of the air by means of the heating system heat exchanger

Automatic basic setting of the temperature set values

The basic setting has been defined at 22 °C.

Every side is automatically (individually) set to this value if the respective belt buckle is not engaged and, at the same time, the driving speed v > 20 km/h is exceeded. This function is carried out only once during ignition ON.

If the rear compartment air conditioning is fitted, it will be informed of this by the automatic air conditioning, as the belt buckles cannot be evaluated by the rear compartment air conditioning.

The DAS can read out the code for the automatic basic setting via the electronic ignition switch (EIS).

1. Heating mode The heat exchanger temperature sensors (B10/2 and B10/3) measure the air temperature at the heating system heat exchanger whilst the interior air temperature sensors (N22b1 and N70b1) determine the respective interior space temperature. In addition, the outside air temperature is measured by the outside air temperature sensor (B14) and the intensity and direction of the sun radiation is measured by the sun sensor (B32/2). The electronic control of the automatic air conditioning pushbutton control module (N22) compares the various measured values with the temperature preselected at the temperature pushbuttons. Depending on demand, the electronic control alters the settings of the automatic air conditioning by operating the duo valves or maintaining the particular setting constant.
2. Cooling mode The evaporator temperature sensor (B10/6) measures the air temperature at the air outlet of the evaporator while the interior temperature sensors (N22b1 and N70b1) detect the particular interior temperature. In addition, the outside air temperature is measured by the outside air temperature sensor (B14) and the intensity and direction of the sun radiation is measured by the sun sensor (B32/2). The electronic control of the automatic air conditioning pushbutton control module (N22) compares the various measured values with the temperature preselected at the temperature pushbuttons. Depending on demand, the electronic control alters the settings of the automatic air conditioning by operating the refrigerant compressor or maintaining the particular setting constant.

On vehicles with rear compartment air conditioning (code 582)

1. Heating mode
2. Cooling mode
3. Heating mode The heat exchanger temperature sensors measure the air temperature at the heater heat exchanger in the rear. The electronic control of the rear compartment air conditioning pushbutton control module compares the measured value with the temperature preselected at the temperature pushbuttons. Depending on demand, the electronic control alters the settings of the rear compartment air conditioning by operating the duo valves or maintaining the particular setting constant.

The vaporizer temperature sensor measures the air temperature at the vaporizer outlet in the rear compartment.

The electronic control of the rear compartment air conditioning pushbutton control module compares the measured value with the temperature preselected at the temperature pushbuttons. Depending on demand, the electronic control alters the settings of the rear compartment air conditioning by operating the refrigerant shut-off valve or maintaining the particular setting constant.

Temperature control, function - GF83.57-P-2000N

MODEL 215

Scheme 138

Function

The electronically controlled refrigeration, heating and ventilation system for automatic air conditioning reaches the desired passenger compartment temperature as quickly as possible or holds it constant by

1. Cooling the air in the evaporator
2. Heating the air in the heater core

1. Heating mode The heat exchanger temperature sensors (B10/2 and B10/3) measure the air temperature at the heater core while the in-car temperature sensors (N22b1 and N70b1) measure the associated temperature in the passenger compartment. In addition the outdoor temperature is measured by the outdoor temperature sensor (B14) and the intensity and direction of the sun radiation by the sun sensor (B32/2). The electronic circuitry in the automatic A/C pushbutton control module (N22) compares the various values with the temperature set with the temperature buttons. The electronic circuitry regulates the automatic air conditioning as required by actuating the duovalves or maintaining the present setting.
2. Air conditioning mode The evaporator temperature sensor (B10/6) measures the air temperature at the evaporator air outlet while the in-car temperature sensors (N22b1 and N70b1) measure the associated temperature in the passenger compartment. In addition the outdoor temperature is measured by the outdoor temperature sensor (B14) and the intensity and direction of the sun radiation by the sun sensor (B32/2). The electronic circuitry in the automatic A/C pushbutton control module (N22) compares the various values with the temperature set with the temperature buttons. The electronic circuitry regulates the automatic air conditioning as required by actuating the A/C compressor or maintaining the present setting.

In-car temperature sensor with aspirator blower function - GF83.57-P-2100-02I

Function

The interior temperature is calculated by two in-car air temperature sensors in the AAC pushbutton control module

1. Temperature sensor in the AAC pushbutton control module
2. Temperature sensor in the roof control unit (the measured value is conveyed to the AAC pushbutton control module via the CAN BUS)

The two in-car air temperature sensors are equipped with an aspirator blower which draws in air from the vehicle interior for the temperature measurement.

With the aspirator blower a continuous circulation of interior air at the in-car air temperature sensors is achieved, therefore guaranteeing a high control accuracy.

Sensor logic

For control of the AAC at outside temperatures < 10°C the value of the in-car air temperature sensor (N70b1) is read into the AAC pushbutton control module (N22) and converted accordingly. At outside temperatures > 10°C both in-car air temperature sensors (N70b1 and N22b1) are read in, with the mean value of both sensors processed in the AAC pushbutton control module (N22).

Heat exchanger temperature sensor, function - GF83.57-P-2101-01I

Function

The heat exchanger temperature sensors are temperature dependent resistors. The resistance values measured are transferred to the automatic A/C pushbutton control module. Here the values measured (actual values) are compared with the temperatures set on the automatic A/C pushbutton control module (left and right separately). From the comparison between the actual values and set values the automatic A/C pushbutton control module calculates the opening time for the duovalves and actuates them separately for the left and right side.

Heat exchanger temperature sensor, function - GF83.57-P-2101-01M

Function

The rear heat exchanger temperature sensors are temperature dependent resistors. The resistance values measured are transferred to the rear A/C pushbutton control module. Here a comparison is made between the values measured (actual values) and the temperatures set on the rear A/C pushbutton control module (left and right separately). From this comparison between the actual values and set values the rear A/C pushbutton control module calculates the opening time for the duovalves and actuates them separately for the left and right side.

Evaporator temperature sensor, function - GF83.57-P-2102-02I

Function

The evaporator temperature sensor is located in the air flow behind the evaporator. It transfers the resistance value measured depending on the temperature at the evaporator to the automatic A/C pushbutton control module.

At an evaporator temperature of 0 °C the A/C compressor is switched off by the automatic A/C pushbutton control module via the CAN bus and left signal-acquisition and actuation module. This prevents the evaporator from icing up.

Evaporator temperature sensor, function - GF83.57-P-2102-02M

Function

The evaporator temperature sensor is located in the air flow behind the rear evaporator. It transfers the resistance value measured depending on the temperature at the evaporator to the rear A/C pushbutton control module.

At an evaporator temperature of 0 °C the refrigerant shutoff valve is actuated directly by the rear A/C pushbutton control module to close the rear refrigerant circuit to prevent the evaporator from icing up.

Outdoor temperature sensor, function - GF83.57-P-2103-01I

Function

The resistance of the outdoor temperature sensor is dependent on the ambient temperature and heat and operates within a range of -40°C to +85°C. The current resistance value is transferred to the automatic A/C pushbutton control module via the left signal-acquisition and actuation module and the CAN bus. The automatic A/C pushbutton control module then changes the temperature settings lightly.

The interrelationship between the outdoor temperature and vehicle speed prevents an erroneously high temperature resulting from heat radiation from the engine from being transferred to the pushbutton control module when the vehicle is standing still or moving slowly. The temperature measured last is used when the ignition is switched off and on and at speeds below 20 km/h. When the ignition is switched off the outdoor temperature value last used for regulation is stored.

Sun sensor function - GF83.57-P-2104-01I

Function

The sun sensor records the intensity and direction of the sun's rays in 4 quadrants and passes on the measured value to the AAC pushbutton control module via the air conditioning bus. Based on this information the AAC pushbutton control module adapts the outlet temperatures and the blower speed. By recording the intensity and direction of the sun's rays in 4 quadrants the air outlet temperature can be controlled separately for the left and right side.

Residual engine heat utilization, function - GF83.75-P-0001N

MODEL 215

Residual engine heat utilization for AAC

The residual engine heat utilization feature allows the vehicle to be heated even when the ignition is switched OFF . The system utilizes the residual engine heat which is blown into the passenger compartment by the blower. Residual engine heat utilization is only possible with the ignition OFF.

After actuating the residual heat button ( ) on the AAC pushbutton control module the following program sequence is preset

1. Duo-valves are regulated
2. Hot water circulation pump ON
3. Blower is automatically supplied with a control voltage of 1.6 V (starts with 6 second delay)
4. Defroster, footwell and blend flaps are adjusted automatically
5. Diverter and fresh air/recirculated air flaps are closed
6. Activated charcoal filter flap open (activated charcoal filter mode not possible)

End of program

1. Press residual heat button ( ) again
2. The operating time expires after 30 minutes (further actuation possible)
3. The word REST flashes on the display when the battery voltage is less than 11 V
4. Ignition ON

During the residual engine heat utilization mode none of the function buttons except the residual heat button ( ), the temperature controls and the rear window defroster button are operable

Function of residual engine heat utilization - GF83.75-P-2000I

MODEL 220

Function of residual engine heat utilization of automatic climate control

Residual engine heat utilization with stationary ventilation allows vehicle to be heated even with ignition OFF . For this, system uses residual heat of engine and leads it via blower into interior. Residual engine heat utilization is only possible with ignition OFF.

After actuation of rest button ( ) on control and operating unit of automatic climate control, the following program process is begun

1. Duo valve regulated
2. Heating water recirculation pump ON
3. Blower is automatically supplied with control voltage of 1.6 V (with 6 second delay)
4. Defroster, footwell and air conditioning flaps are automatically adjusted.
5. Diverter, fresh/circulating air flaps are closed
6. Activated charcoal canister flap open (no activated coal filter operation possible)

Function of residual engine heat utilization of rear air conditioning system

Residual engine heat utilization with stationary ventilation allows vehicle to be heated even with ignition OFF . For this, system uses residual heat of engine and leads it via blower into interior. Residual engine heat utilization is only possible with ignition OFF.

After actuation of rest button ( ) on control and operating unit of automatic climate control, the following program process is begun

1. Duo valve regulated
2. Auxiliary coolant pump ON
3. Blower is automatically supplied with control voltage of 1.2 V (immediately after switching on)
4. Actuator motor (manual flap adjustment possible)
5. Refrigerant shut-off valve closed

Program end

1. Repeated actuation of rest button ( )
2. Process of time function of 30 minutes (further actuation is possible). If rear air conditioning system is in REST mode at the same time, operation duration is limited to 15 minutes (current consumption)
3. With battery voltage below 11 V, REST flashes in display
4. Ignition ON

During functioning of residual engine heat utilization, no function buttons are accepted apart from rest button ( ) nominal value adjusters and rear window heater button

Program end

1. Repeated actuation of rest button ( )
2. Process of time function of 30 minutes (further actuation is possible). If rear air conditioning system is in REST mode at the same time, operation duration is limited to 15 minutes (current consumption)
3. With battery voltage below 11.5 V REST display moves up in display and a battery symbol appears.
4. With battery voltage below 11.3 V system switches off.
5. Ignition ON

During functioning of residual engine heat utilization only rest button ( ), temperature button ( ) and air distribution regulator are accepted