Climate Control -- Basic Knowledge -- 251 Chassis: Overview Mercedes-Benz R-class W251 facelift

Booster blower, component description - GF83.10-P-2040RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Scheme 137

Location

The booster blower is located between the two front seats below the center tunnel.

Design

1. Booster blower motor (M2/1)
2. Rear air distribution flap actuator motor (M2/21)
3. Booster blower electronic blower controller (N29/2)
4. Center rear interior temperature sensor (B10/7)

Task

The booster blower is used to improve the ventilation of the rear passenger compartment in order to achieve faster cool down or heating.

The blower stage in the rear can be controlled independently through the booster blower

Booster adapter, component description - GF83.10-P-2041RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Exemplified on model series 251 with comfort automatic air conditioning, code 581

Scheme 138

Location

The booster adapter is located between the two front seats below the center tunnel.

Design

1. Booster adapter
2. Rear air distribution flap actuator motor (M2/21)

Task

The rear air distribution flap actuator motor in the booster adapter serves for selected guidance of the air flow in the rear passenger compartment.

Blower, component description - GF83.10-P-2050RT

MODEL 251.1/0 up to Model Year 8

Scheme 139

Location

The blower motor is located on the right below the glove compartment in the air conditioner housing.

Task

The blower motor blows fresh air or air from the interior compartment through the air conditioner housing into the vehicle interior.

Function

Depending on the blower stage

1. the AAC control and operating unit (N22) or
2. the comfort AAC control and operating unit (N22/7)

sends a control signal, via the Local Interconnect Network (LIN), to the blower regulator (A32n1).

The blower regulator then regulates the operating voltage for the blower regulator, depending on the control signal.

In engine residual heat utilization operation the blower motor recirculates the air in the interior.

Blower, component description - GF83.10-P-2050RTH

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on model series 251

Scheme 140

Location

The rear air conditioning blower motor is located in the left rear directly at the rear air conditioner.

Task

The rear air conditioning blower motor blows fresh air or air from the interior compartment through the rear AC housing into the vehicle interior.

Function

Depending on the blower stage

1. the comfort AAC [KLA] control and operating unit (N22/7) or
2. the RCP [HBF] control unit (N72/2)

sends a control signal via the local interconnect network (LIN) to the rear air conditioning blower regulator (N29/7).

The rear air conditioning blower regulator then regulates the operating voltage for the rear air conditioning blower motor depending on the control signal.

Blower regulator, component description - GF83.10-P-2051RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Scheme 141

Location

The blower regulator is located on the right below the glove compartment and is attached directly to the blower motor (A32m1).

Task

The blower regulator is connected with the AAC [KLA] control and operating unit (N22) to exchange data over the local interconnect network (LIN).

The blower regulator controls the voltage supply to the blower motor to match the blower stage set on the AAC [KLA] control and operating unit.

Function

The AAC [KLA] control and operating unit forwards a control voltage from 0 to 100% to the blower regulator. This then regulates the operating voltage for the blower motor to match the control voltage applied from 0 to 100%. This facilitates control of the blower motor speed from 0-100%.

The blower motor regulator (operating voltage) is influenced by the following factors

1. Blower output setting (AUTO/manual)
2. AC OFF (ON/OFF)
3. Mode status (heating, cooling)
4. Intensity of sun
5. Coolant temperature
6. Vehicle speed
7. Window, sliding roof, tilting roof position
8. Vent window position
9. Panoramic sliding roof position
10. Ambient temperature
11. Fresh air and air recirculation flap position
12. Flap positions (air distribution)
13. Residual engine heat utilization function, stationary ventilation function
14. Version coding

Blower regulator, component description - GF83.10-P-2051RTH

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on model series 251

Scheme 142

Location

The blower regulator is located in the left rear and is directly attached to the rear air conditioning blower motor (M2/29) of the rear air conditioner.

Task

The rear air conditioning blower regulator is connected to the comfort AAC [KLA] control and operating unit (N22/7) via local interconnect network (LIN) for data exchange purposes.

The rear air conditioning blower regulator regulates the voltage supply of the blower motor depending on the blower stage set on the comfort AAC [KLA] control and operating unit or on the RCP [HBF] control unit (N72/2).

Function

The comfort AAC [KLA] control and operating unit sends a control voltage of 0 to 100% to the rear air conditioning blower regulator. This then regulates the operating voltage for the blower motor depending on the control voltage applied from 0 to 100%. This facilitates control of the blower motor speed from 0-100%.

The blower motor regulator (operating voltage) is influenced by the following factors

1. Blower output setting (AUTO/manual)
2. AC OFF (ON/OFF)
3. Mode status (heating, cooling)
4. Coolant temperature
5. Position of windows, tilting/sliding roof or panoramic sliding roof
6. Vent windows position
7. Outside temperature
8. Air humidity (dew point)
9. Pollutant concentration
10. Flap positions (air distribution)
11. Residual engine heat utilization function, stationary ventilation function
12. Version coding

Blower regulator, component description - GF83.10-P-2051RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Exemplified using model series 164

Scheme 143

Location

The blower regulator is located on the right below the glove compartment and is attached directly to the blower motor (A32m1).

Task

The blower regulator is connected via the local interconnect network (LIN) to the comfort AAC control and operating unit (N22/7) for data exchange purposes.

The blower regulator regulates the voltage supply to the blower motor depending on the blower stage set on the comfort AAC [KLA] control and operating unit.

Function

The comfort AAC control and operating unit sends a control voltage of 0 to 100% to the blower regulator. This regulates the operating voltage for the blower motor depending on the control voltage applied from 0 to 100%. This facilitates control of the blower motor speed from 0-100%.

The blower motor regulator (operating voltage) is influenced by the following factors

1. Blower output setting (AUTO/manual)
2. AC OFF (ON/OFF)
3. Mode status (heating, cooling)
4. Sun intensity, direction of the solar radiation
5. Coolant temperature
6. Vehicle speed
7. Window, tilting/sliding roof
8. Vent window setting
9. Panoramic sliding roof setting
10. Ambient temperature
11. Air humidity (dew point)
12. Emission content
13. Fresh air/recirculation flap setting
14. Flap settings (air distribution)
15. Residual engine heat function, stationary ventilation function
16. Version coding

Emissions sensor, component description - GF83.10-P-2191RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Location

The emissions sensor is installed on the right firewall.

Scheme 144

Task

The values of the emissions sensor are processed by the front air conditioning. It senses the concentration of the air pollutants carbon monoxide and nitrogen oxide. The comfort AAC [KLA] control and operating unit (N22/7) uses the measured values of the emissions sensor to control the recirculated air.

If the air pollutant concentration is too high, only the inside air is recirculated and the supply of outside air is prevented.

This function is not available with A/C OFF

Function

The emissions sensor operates reactively

The air recirculation flap is not closed until after the sensor has detected an increase of the CO and NO x values. Although this only takes a few seconds, part of the pollutants might have already reached the interior compartment during this time. To prevent this from happening, the activated charcoal filter retains the pollutants until the recirculation door is closed.

Actuator motors, component description - GF83.10-P-2201RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Scheme 145

Location

The actuator motors are located in the A/C housing.

task

General determinations on actuator motor and flap controls

Continuous positioning of the flaps.

The following release function is realized for each flap in the automatic air conditioning to prevent the actuator motors from operating continuously in the controlled range.

Release function: Once a position has been adjusted, then until the next change, the blow air nominal temperature, for example, must change by so much that the release value going above or below it is either not reached or exceeded.

Final values are approached directly (0%, 100%).

Anti-fogging function

The anti-fogging function prevents the windshield and side windows from fogging up after starting the engine by blowing the moist air, immediately after starting, into the vehicle footwell instead of against the windows.

Center outlet flap actuator motor

The center outlet flap actuator motor actuates the air flaps for controlling the air flow to the center nozzle.

The center outlet flap actuator motor is actuated by the AAC control and operating unit (N22) depending on the air outlet temperature desired at the center nozzle.

Actuation for "Defrost" Center outlet flap 0% (closed)

Actuation for "Rest" according to control

Actuation for "0" remain in previous condition

Actuation for ignition OFF remain in previous condition

Automatic air flap control

The air flaps are opened according to a defined characteristic up to 100% by the center outlet flap actuator motor, depending on the following values

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature
4. Footwell flap position

Air flap control via the center nozzle

In manual mode the air flap settings are determined by the selector on the center nozzle.

Left blending air flap actuator motor and right blending air flap actuator motor

The left and right blending air flap actuator motor serves for adjustment of the heating and air conditioning ventilation temperature.

The left and right blending air flap actuator motors are actuated according to a defined characteristic by the AAC control and operating unit depending on the position of the temperature selector wheel and the actual interior temperature thereby moving the blending air flaps. The flaps open or close the air passage through the heater heat exchanger in order to mix heated and fresh or cooled air in the correct proportions required to achieve the desired interior temperature.

The set flap angle for the blending air flaps is determined by the ACC control and operating unit, depending on the following information

1. regulated target temperature on the temperature selector wheel
2. the in-car temperature measured by the in-car temperature sensors
3. Coolant temperature

Blending air flaps closed No air through mixing chamber and therefore no air heating

Blending air flaps opened All air passes through the mixing chamber with maximum air heating

Left and right defroster flaps actuator motor

The left and right defroster flaps actuator motors actuate the defroster vent flap for control of the air flow to the windshield defroster vents and side window defroster vents. The window defroster button on the AAC control and operating unit can be pressed to actuate the left and right defroster flaps actuator motors via LIN bus, thereby actuating the defroster vent flaps.

With "defrosting" and "0", the defroster vent flaps are 100% open.

Manual flap control

(12 o'clock partitioning through actuation of air distributor duct button)

Automatic flap control

The defroster vent flaps are opened linearly up to 100% depending on the following values

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature
4. Relative humidity

Left and right footwell flaps actuator motor

The left and right footwell flaps actuator motors actuate the footwell flaps for control of the air flow to the front and rear footwells.

When the air distribution buttons on the AAC control and operating unit are pressed, the left and right footwell flap actuation motors are actuated over the LIN bus, thereby actuating the footwell flaps, which can assume the following positions depending on the requirements

Actuation for "Defrost" Footwell flaps 0% (closed)

Actuation for "Rest" according to control

Actuation for "0" No change

Manual flap control

(12 o'clock partitioning through actuation of air distributor duct button)

Automatic footwell flap control

The footwell flaps are opened linearly up to 100%, depending on the following values

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature

Fresh air/air recirculation flaps actuator motor

The actuator motor facilitates the closing or opening of the fresh air supply by actuating the fresh air/air recirculation flaps.

The fresh and air recirculation flaps actuator motor is actuated by pressing the air recirculation switch (N22s2) on the AAC control and operating unit.

In air recirculation mode, the recirculation flap is open and the fresh air flap is closed. Air is drawn out of the vehicle interior into the A/C housing by the blower.

In fresh air mode, the fresh air flap is open and the recirculated air flap is closed. Fresh air is drawn into the automatic air conditioning housing by the blower.

When the air recirculation switch is actuated manually, the system immediately switches to 100% recirculated air for a limited time. This is displayed by the function LED. Time limit function

1. after 30 min at outdoor temperatures above approx. 7°C
2. after 5 min at outside temperatures below approx. 7°C
3. after 5 min. with AC OFF.

100% automatic recirculated air is possible for 30 min after switching ON the ignition. After the time has elapsed, the system switches to 80% recirculated air mode or fresh air mode, depending on the conditions.

If automatic recirculated air is required after engine ON, fresh air will be circulated initially for 30 seconds. Then, operation is first continued automatically with 80% recirculated air and 10 s later, also with 100% automatically recirculated air, depending on the requirement.

Tunnel function

Activation of the tunnel function

Only possible where the recirculated air LED is not illuminated. Actuation of the air recirculation switch for longer than 1.5 s Reaction: fresh air and air recirculation flaps are driven into air recirculation position. Now the 4 windows and the tilting/sliding roof are closed in a staggered manner.

If the recirculated air LED is canceled manually or by the automatic timer, the fresh air and air recirculation flap goes to the fresh air position, however, the windows and sliding roof remain closed.

Deactivation of tunnel function

Only possible where the recirculated air LED is illuminated. Actuation of the air recirculation switch for longer than 1.5 s Reaction: Fresh air and air recirculation flaps are driven into fresh air position. Now the 4 windows and the tilting/sliding roof are opened in a staggered manner.

If the recirculated air LED is reset manually (actuation of air recirculation switch for less than 1.5 s), the fresh air and air recirculation flap is moved to the recirculated air position.

Special functions of the fresh air/air recirculation control

1. The function AC OFF does not allow any automatic nor emissions-controlled recirculated air.
2. Only fresh air mode is possible in the defrosting function.
3. In the function "0" 100% recirculated air applies.
4. Manual recirculated air is deleted after ignition OFF.
5. Manual or automatic recirculated air is possible in the "Rest" position.

Actuator motors, component description - GF83.10-P-2201RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Scheme 146

Scheme 147

Location

The actuator motors are located on the A/C housing and are located at the respective positions as shown in the picture above.

Task

General information on actuator motors and flap control

Continuous positioning of the flaps.

The following release function is realized for each flap in the automatic air conditioning to prevent the actuator motors from operating continuously in the controlled range.

Release function: This is a position which, once set, must change so much up to the next change, e.g. blower stage temperature setting, that the release value above or below is exceeded or dropped below. Final values are approached directly (0%, 100%).

Anti-fogging function

The anti-fogging function prevents the windshield and side windows from fogging up after starting the engine thanks to the fact that moist air is not guided directly against the windows after starting, but instead into the footwell of the vehicle.

Left center air flap actuator motor and right center air flap actuator motor

The left center air flap actuator motor and the right center air flap actuator motor operate the particular air flap that controls the air flow to the center nozzles separately for left and right.

Depending upon the desired air outlet temperature at the center nozzle, the left center air flap actuator motor and the right center air flap actuator motor are actuated via the comfort AAC [KLA] control and operating unit (N22/7).

Actuation for "Defrost" Center outlet flaps 0% (closed)

Actuation for "Rest" according to control

Actuation for "0" remain in previous condition

Actuation for ignition OFF remain in previous condition

Automatic air flap control

Depending upon the following variables, the air flaps can be opened up to 100% by the left center air flap actuator motor and the right center air flap actuator motor in line with a defined characteristic

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature
4. Footwell flap position

Air flap control via the center nozzle

In manual mode the air flap settings are determined by the selector on the center nozzle.

Left blending air flap actuator motor and right blending air flap actuator motor

The left blending air flap actuator motor and the right blending air flap actuator motor are used to set the ventilation temperature of the heater and the air conditioning separately for left and right.

The actuator motors of the blending air flaps are actuated via the comfort automatic air conditioning control and operating unit depending on the temperature buttons selected and the actual interior temperature according to defined characteristics and move the blending air flaps. The flaps open or close the passage of air through the heating system heat exchanger in order to mix hot air with fresh air or cooled air in order to achieve the desired in-car temperature.

The specified flap angles of the blend air flaps are determined by the comfort automatic air conditioning control and operating unit as a function of the following information

1. regulated target temperature on the temperature selector wheel
2. in-car temperature measured by the in-car temperature sensors
3. Coolant temperature

Blending air flaps closed No air through mixing chamber and therefore no air heating

Blend air flaps open All air flows through the mixing chamber with maximum heating of air

Left defroster vent flap actuator motor and right defroster vent flap actuator motor

The left defroster vent flap actuator motor and the right defroster vent flap actuator motor operate the particular defroster vent flap that controls the air flow to the windshield defroster vent and the side window defroster vents separately for each side. By pressing the window defrost switch on the comfort AAC control and operating unit, the defroster vent flap actuator motors are actuated and the defroster vent flaps are operated, which then adopt the following positions at various requirements

Actuation during "Defrosting" Defroster vent flap open 100%.

Actuation for "0" Defroster vent flap open 100%.

Manual flap control

(division as clock by actuating the air distribution wheel)

Automatic flap control

The defroster vent flaps are opened linearly up to 100% depending on the following values

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature
4. Relative humidity

Left footwell flap actuator motor and right footwell flap actuator motor

The left footwell flap actuator motor and the right footwell flap actuator motor operate the particular footwell flap that controls the air flow to the front footwell and the rear legroom separately for each side.

By pressing the footwell air distribution button in the comfort AAC control and operating unit, the left footwell flap actuator motor and the right footwell flap actuator motor are actuated. The footwell flaps adopt the following positions at various requirements

Actuation for "Defrost" Footwell flaps 0% (closed)

Actuation for "Rest" according to control

Actuation for "0" no change

Manual flap control

(division as clock by actuating the air distribution wheel)

Automatic footwell flap control

The footwell flaps are opened linearly up to 100%, depending on the following values

1. Blending air flap setting
2. Coolant temperature
3. Evaporator temperature

Fresh air/air recirculation flaps actuator motor

The fresh air/air recirculation flaps actuator motor is used to close or open the fresh air supply by actuating the fresh air/air recirculation flaps.

The fresh air/air recirculation flaps actuator motor is actuated by pressing the air recirculation switch (N22/7s2) on the comfort AAC control and operating unit.

In air recirculation mode, the recirculation flap is open and the fresh air flap is closed.

Air is suctioned from the vehicle interior into the comfort automatic air conditioning housing by the blower.

In fresh air mode, the fresh air flap is opened and the recirculated air flap is closed. Fresh air is suctioned into the comfort automatic air conditioning housing by the blower.

If the air recirculation switch is operated manually, the system immediately enters time-limited 100% recirculated air. This is displayed by the function LED. Time limit function

1. after 30 min at outdoor temperatures above approx. 7°C
2. after 5 min at outside temperatures below approx. 7°C
3. after 5 min following AC OFF.

100% automatic recirculated air is possible for one time only for 30 min after ignition is switched "ON". After the time has elapsed, the system switches to 80% recirculated air mode or fresh air mode, depending on the conditions.

If automatic recirculated air is required after engine ON, fresh air will be circulated initially for 30 seconds. Then, operation is first continued automatically with 80% recirculated air and 10 s later, also with 100% automatically recirculated air, depending on the requirement.

Tunnel function

Activation of the tunnel function

Only possible where the recirculated air LED is not illuminated. Actuation of the air recirculation switch for longer than 1.5 s Reaction: fresh air and air recirculation flaps are driven into air recirculation position. Now the 4 windows and the tilting/sliding roof are closed in a staggered manner.

If the recirculated air LED is extinguished manually or by the automatic timer, the fresh air and air recirculation flap moves to the fresh air position, however, the windows and the sliding roof remain closed.

Deactivation of tunnel function

Only possible where the recirculated air LED is illuminated. Actuation of the air recirculation switch for longer than 1.5 s Reaction: Fresh air and air recirculation flaps are driven into fresh air position. Now the 4 windows and the tilting/sliding roof are opened in a staggered manner.

If the recirculated air LED is reset to manual mode (pressing the air recirculation switch for less than 1.5 s), only the fresh air/air recirculation flap is set to recirculated air position.

Special functions of the fresh air/air recirculation control

1. The function AC OFF does not allow any automatic nor emissions-controlled recirculated air.
2. Only fresh air mode is possible in the defrosting function.
3. In the function "0" 100% recirculated air applies.
4. Manual recirculated air is deleted after ignition OFF.
5. No manual or automatic recirculated air is possible in the rest function.

Coolant shutoff motor, component description - GF83.20-P-2117RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on BR 251

Scheme 148

Location

The rear air conditioning coolant shutoff motor is located in the left rear above the wheelhouse.

Task

If only front air conditioning functions are selected via the comfort AAC (KLA) control and operating unit (N22/7), the coolant shutoff motor shuts off the coolant supply to the rear air conditioning.

Heating system heat exchanger, component description - GF83.20-P-3123RT

MODEL 251.1/0 up to Model Year 8

Scheme 149

Location

The heating system heat exchanger is located behind the instrument panel in the A/C housing.

Task

The heating system heat exchanger warms the air flow, which is directed to the vehicle interior via the various defroster, ventilation and heater vents.

Function

Heated coolant flows through the heating system heat exchanger when heat is required.

The heat is conducted to the outside via the coiled pipes and lamella. This in turn warms the passing airflow, which is directed to the vehicle interior via the various defroster, ventilation and heater vents.

Dew point sensor, component description - GF83.30-P-2129RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Location

The dew point sensor is located down at the front of the automatic air conditioning box.

Scheme 150

Task

The dew point sensor is used to detect the air humidity of the drawn in outside air and thus to better control the evaporator temperature. When the outside air is humid, the evaporator temperature is regulated to a lower setting than when the outside air is dry to improve the dehumidification output. Thus, the interior climate is perceived as more pleasant. Because the power consumption is lower when the air is dry, fuel consumption is reduced as well.

Design

The dew point sensor comprises the following elements

1. Measuring cell for humidity
2. Electrical connector
3. Electronic printed circuit board with processor

Function

The dew point sensor measures the air humidity of the suctioned air and forwards this measured value to the comfort AAC [KLA] control and operating unit (N22/7), thereby allowing it to regulate a demand-based, not too dry interior climate. The calculated measured value is additionally placed by the comfort AAC control and operating unit on the CAN interior. The left front door control unit (N69/1) and the right front door control unit (N69/2) read in this value to obtain the most favorably adjusted heated outside mirror.

Scheme 151

Scheme 152

Table of contents for automatic climate control function description - GF83.40-P-0995GM

MODEL 164.1 as of model year 09/YoM 08 model refinement package

MODEL 164.8, 251.0/1 as of model year 09/YoM 08

Convenience automatic air conditioning (C-AAC) functional description table of contents - GF83.40-P-0996RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Table of contents, automatic air conditioning (AAC) function description - GF83.40-P-0999RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Automatic air conditioning box, component description - GF83.40-P-2010RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Exemplified on model series 164

Scheme 153

Location

The automatic air conditioning box is below the instrument panel.

Task

The automatic air conditioning box distributes the air that is required to ventilate the vehicle to the relevant air ducts and vents depending on the interior temperature that is required.

The air ducting depends on various operating conditions such as

1. Heating mode
2. Cooling mode
3. Normal mode
4. Blending air mode

Comfort automatic air conditioning box, component description - GF83.40-P-2011RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Exemplified on model series 164

Scheme 154

Location

The automatic air conditioning housing is below the instrument panel.

Task

The automatic air conditioning box distributes the air that is required to ventilate the vehicle to the relevant air ducts and vents depending on the interior temperature that is required.

The air ducting depends on various operating conditions such as

1. Heating mode
2. Cooling mode
3. Normal mode
4. Blending air mode
5. Emission-controlled air recirculation
6. Air humidity-controlled cooling

Condenser, component description - GF83.40-P-2188RT

MODEL 251.1/0 up to Model Year 8

Scheme 155

Location

The condenser is located behind the radiator grille, immediately in front of the radiator.

Task

The condenser transforms the state of aggregation of the refrigerant coming from the evaporator from gaseous into liquid.

Function

In the condenser, the hot coolant is pressed in from above, coming from the refrigerant compressor (A9). Coiled pipes and fins absorb this heat extremely rapidly and give it off into the outside air flowing through the condenser.

This in turn cools the refrigerant. While the refrigerant is cooling down to a specific, pressure-sensitive temperature, the refrigerant condenses and is liquified. The liquid refrigerant exits at the bottom of the condenser and flows into the fluid reservoir.

Evaporator, component description - GF83.40-P-2189RT

MODEL 251.1/0 up to Model Year 8

Scheme 156

Location

The evaporator is located in the A/C housing behind the instrument panel.

Task

The evaporator serves for cooling, dehumidifying and purifying the interior compartment air.

Design

Disk evaporator made from soldered semicircular disks with corrugated ribs.

Function

The liquid refrigerant under high pressure is injected into the evaporator through the expansion valve.

The refrigerant evaporates, thereby absorbing the quantity of heat required for evaporation from the air flowing past the evaporator.

The soldered semicircular disks with corrugated ribs provide a large evaporation surface and guarantee rapid heat exchange.

The humidity which condenses during the air cooling process is diverted by way of condensed water drainage hoses into the open.

Evaporator, component description - GF83.40-P-2189RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Scheme 157

Location

The evaporator of the rear air conditioning is located in the rear AC housing at the left rear.

Task

The evaporator serves for cooling, dehumidifying and purifying the interior compartment air.

Design

Disk evaporator made from soldered semicircular disks with corrugated ribs.

Function

The liquid refrigerant under high pressure is injected into the evaporator through the expansion valve.

The refrigerant evaporates, thereby absorbing the quantity of heat required for evaporation from the air flowing past the evaporator.

The soldered semicircular disks with corrugated ribs provide a large evaporation surface and guarantee rapid heat exchange.

The humidity which condenses during the air cooling process is diverted by way of condensed water drainage hoses into the open.

Expansion valve, component description - GF83.40-P-2190RT

MODEL 251.1/0 up to Model Year 8

Scheme 158

Location

The expansion valve is located in the engine compartment at the left rear.

Task

The expansion valve sprays liquid refrigerant into the evaporator. The injection quantity depends on the pressure and temperature of the refrigerant supplied.

Function

When the refrigerant compressor (A9) is switched on, the pressure in the evaporator decreases causing a diaphragm in the expansion valve to arch. The diaphragm motion is transferred to a linkage. The linkage presses the valve ball out of its seat opening the valve. The opened valve enables the refrigerant to be sprayed into the evaporator.

Since the motion of the diaphragm depends on the suction pressure, as well as the temperature at the evaporator outlet, only the quantity of refrigerant which can evaporate optimally is injected.

Expansion valve, component description - GF83.40-P-2190RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on BR 251

Scheme 159

Location

The expansion valve is located in the left rear at the rear air conditioner.

Task

The expansion valve sprays liquid refrigerant into the evaporator. The injection quantity depends on the pressure and temperature of the refrigerant supplied.

Function

When the refrigerant compressor (A9) is switched on, the pressure in the evaporator decreases causing a diaphragm in the expansion valve to arch. The diaphragm motion is transferred to a linkage. The linkage presses the valve ball out of its seat opening the valve. The opened valve enables the refrigerant to be sprayed into the evaporator.

Since the motion of the diaphragm depends on the suction pressure, as well as the temperature at the evaporator outlet, only the quantity of refrigerant which can evaporate optimally is injected.

Engine/AC electric suction fan, component description - GF83.40-P-2192RT

MODEL 251.1/0 up to Model Year 8

Scheme 160

Location

The suction fan is located behind the radiator.

Task

The suction fan serves for cooling the coolant from the engine and the refrigerant from the air conditioning.

Function

Depending on the refrigerant pressure, and/or the coolant temperature and outside temperature, the speed of the engine and AC electric suction fan with integrated control is increased continuously.

Actuation of the engine and AC electric suction fan with integrated control is calculated for the front refrigerant circuit by the AAC [KLA] control and operating unit (N22) or by the comfort AAC [KLA] control and operating unit (N22/7).

The AAC [KLA] control and operating unit or comfort AAC [KLA] control and operating unit sends the information over CAN-B to the EIS [EZS] control unit (N73) and then over CAN-C to the ME-SFI [ME] control unit (N3/10). The ME-SFI [ME] control unit also receives the current coolant temperature via the coolant temperature sensor (B11/4) and forwards this information for regulation to the control unit integrated in the engine and AC electric suction fan with integrated control.

The front SAM control unit (N10) receives the refrigerant pressure from the refrigerant pressure sensor (B12) and the outside temperature from the outside temperature display temperature sensor (B14).

The input information received by the control unit integrated into the engine and AC electric suction fan with integrated control are compared against stored values and if necessary the rotational speed of the engine and AC electric suction fan with integrated control is increased to 100%.

The engine and AC electric suction fan with integrated control runs at 25% output when the air conditioning systems are switched on for basic ventilation.

The basic ventilation can be switched off under the following conditions

1. At an outside temperature < or = 15°C
2. At a ground speed > 70 km/h or 45 mph

Each pressure-dependent speed of the engine and AC electric suction fan with integrated control is retained.

Cut in of the electric suction fan engine and AC with integrated control

The electric suction fan engine and AC with integrated control is actuated at the following values

1. Refrigerant pressure < 12 bar = Suction fan ON (25%)
2. Refrigerant pressure > 20 bar = Suction fan ON (100%)
3. Refrigerant pressure 12 to 20 bar = (25 to 100%)

A run-on time of 60 s can be set in order to ensure that the engine and AC electric suction fan with integrated control will continue to operate even where the refrigerant compressor is temporarily switched off by the anti-icing protection.

Refrigerant pressure sensor, component description - GF83.40-P-2193RT

MODEL 251.1/0 up to Model Year 8

Scheme 161

Location

The refrigerant pressure sensor is located in the engine compartment at the front left on the high pressure line between the refrigerant compressor (A9) and condenser.

Task

The refrigerant pressure sensor records the refrigerant pressure. The reading is read in by the AAC control and operating unit (N22) or comfort AAC control and operating unit (N22/7).

Detecting the refrigerant pressure

The refrigerant pressure sensor records the refrigerant pressure and forwards the determined value over the front SAM control unit (N10) and CAN-B to the AAC [KLA] control and operating unit or the comfort AAC [KLA] control and operating unit. This value is compared against a stored pressure curve.

The refrigerant pressure sensor operates in a pressure value range of 0 to 35 bar.

Left refrigerant compressor cutout

The refrigerant compressor is cut out if the following values are given.

1. Refrigerant pressure < 1.7 bar = Refrigerant compressor OFF
2. Refrigerant pressure > 30 bar = Refrigerant compressor OFF

Cut-in of electric suction fan engine and AC with integrated control (M4/7)

The electric suction fan engine and AC with integrated control is actuated at the following values

1. Refrigerant pressure < 12 bar = Suction fan OFF
2. Refrigerant pressure > 20 bar = Suction fan ON (100%)
3. Refrigerant pressure 12 to 20 bar = Continuously linear speed increase of suction fan (20 to 100%)

The following values apply to hot countries

1. Refrigerant pressure < 10 bar = Suction fan OFF
2. Refrigerant pressure > 18 bar = Suction fan ON (100%)
3. Refrigerant pressure 10 to 18 bar = Continuously linear speed increase of suction fan (20 to 100%)

Fluid reservoir, component description - GF83.40-P-2196RT

MODEL 251.1/0 up to model year 08/YoM 07

Scheme 162

Location

The fluid reservoir is located below the condenser (1).

Task

1. Filtering chemical and mechanical impurities out of the refrigerant
2. Volume storage for the refrigerant
3. Draining of the refrigerant

Function

The liquefied refrigerant enters the fluid reservoir under pressure and flows through a stainless-steel fabric layer to the filter block. The filter block can absorb a specific amount of water.

The filter block's pores are matched exactly to the molecular size of the refrigerant. Thus the refrigerant can flow through the filter block.

All other substances are held back and retained. The cleansed refrigerant then flows through a rising pipe to the expansion valve.

Component description for automatic air conditioning control and operating unit - GF83.40-P-3000GM

MODEL 164.1 as of model year 2009 except CODE (581) Comfort automatic air conditioning/YoM 08 model refinement package

MODEL 164.8,251.0/1 as of model year 2009 except CODE (581) Comfort automatic air conditioning/YoM 08

Shown on model 251 without code (494) USA version

Scheme 163

Location

The control and operating unit is located in the center console.

Shown on model 251 with code (494) USA version

Scheme 164

Location

The control and operating unit is located in the center console.

Design

The control and operating unit contains the following controls and displays

1. Left temperature selector wheel (1)
2. "AUTO" button (2)
3. Defrosting button (3)
4. Increase air volume button (4)
5. Windshield air distribution button (5)
6. "A/C", "REST" button (6)
7. Right temperature selector wheel (7)
8. "REAR" button (8)
9. Center air distribution button (9)
10. Footwell air distribution button (10)
11. Air volume indicator (11)
12. Reduce air volume button (12)
13. "OFF" button (13)
14. In-car temperature sensor (N22b1)
15. Heated rear window switch (N22s1)
16. Air recirculation switch (N22s2)

Task

The control and operating unit has the following tasks

1. Operation of the vehicle's climate control
2. Reading in of sensors and signals
3. Evaluation of input factors
4. Actuation of components

Operation of the vehicle's climate control

The control and operating unit enables the following operations

1. Switching the automatic air conditioning on and off
2. Interior temperature selection separated for the left and right side
3. Manual blower control and air distribution
4. Automatic blower control and air distribution
5. Defrost function
6. Residual heat utilization
7. Recirculated air mode
8. Heated rear window (R1) actuation

It is operated with the following controls

1. Temperature selector wheels
2. "AUTO" button
3. Defrosting button
4. Air volume buttons
5. Air distribution buttons
6. "A/C", "REST" button
7. "REAR" button
8. "OFF" button
9. Heated rear window switch
10. Air recirculation switch

Temperature selector wheels

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel. The selected specified temperature is displayed via LEDs at the border of the temperature selector wheel.

"AUTO" button

The air volume and the air distribution are regulated automatically when the AUTO button is pressed. If the automatic operation is activated, the LED in the "AUTO" button lights up.

The blower level on the USA version is higher than on the Economic Commission for Europe (ECE) version

Defrosting button

Pressing the defroster button sets the temperature to "maximum" and the air flow is distributed to the defroster and side air vents. All the other flaps are closed. The blower output is regulated to match the coolant temperature.

If the function is activated, the light emitting diode in the defroster button illuminates.

Air volume buttons

Pressing the respective air volume button enables the air volume delivered to the interior to be set manually.

The selected setting is displayed in the air volume display.

Air distribution buttons

Pressing the respective air distribution button enables the distribution of the air flowing into the interior to be set manually.

If the function is activated, the LED in the respective air distribution button lights up.

"A/C", "REST" button

With circuit 15 ON, press the "A/C", "REST" button to switch the refrigerant compressor (A9) (not on model 164.195) or the electric refrigerant compressor control unit (N19/4) (on model 164.195) on or off. All other functions are retained.

The LED in the "A/C", "REST" button lights up with the refrigerant compressor switched on.

With circuit 15C or circuit 15R ON, press the "A/C", "REST" button to activate the residual engine heat utilization system function. When the function is activated, the LED illuminates.

"REAR" button

The "REAR" button can be used to change the rear temperature values via the control and operating unit. When the REAR button is pressed, the specified rear temperature values appear in the right temperature selector wheel. The blower setting is not visible. The function is stopped automatically if operation is not performed within approx. t = 5 s or the "REAR" button is pressed again.

During operation with the remote control, an adjustment of the specified values in the rear is not possible.

The rear values are stored in the control and operating unit.

With code (494) USA version, the "REAR" button is provided with the lettering "REAR" instead of a pictogram

"OFF" button

The automatic air conditioning can be switched off completely or switched back on by pressing the "OFF" button.

The LED in the "OFF" button lights up when the automatic air conditioning is switched off.

Rear window heater switch

Air recirculation switch

When the air recirculation switch on the control and operating unit is pressed for t < 1.5 s, the fresh air/air recirculation flap is closed, and thus the supply of outside air is prevented. The air only circulates in the vehicle interior and unpleasant odors and harmful gases are kept out. The LED in the air recirculation switch comes on.

The rear window heater is switched on when the rear window heater switch is pressed. The LED lights up during operation of the rear window heater.

The operating time of the rear window heater is calculated by the rear SAM control unit (N10/8) depending on the outside temperature and the vehicle speed

Pressing the air recirculation switch for t > 1.5 s activates comforrecirculation closing. In the process the windows, the tilting/sliding roof (with code (414) Power glass tilting/sliding roof) or the panoramic sunroof (model 251 with code (413) Panoramic glass sunroof with top sliding sunroof) and the vent windows (model 164.8 and model 251 with code (848) Power side vent windows) are closed automatically.

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

With code (460) Canada version and code (494) USA version, convenience recirculation closing is not possible

The detailed convenience recirculation closing procedure is described in the convenience feature function (KFB)

Reading in of sensors and signals

The input factors are read in with the following connections

1. Direct line
2. Interior CAN

Direct line

The following sensors are read in via a direct line

1. Interior air temperature sensor
2. Evaporator temperature sensor (B10/6)
3. Left side outlet temperature sensor (B10/31)
4. Right side outlet temperature sensor (B10/32)
5. Left center outlet temperature sensor (B10/33)
6. Right center outlet temperature sensor (B10/34)
7. Left footwell temperature sensor (B10/35)
8. Right footwell temperature sensor (B10/36)
9. Refrigerant pressure sensor (B12)
10. Outside temperature indicator temperature sensor (B14)
11. Sun sensor (B32)

Interior CAN

The following signals and sensors are read in via interior CAN

By the instrument cluster (A1)

1. Ground speed

By the rear SAM control unit

1. Rear door locking unit (A72)
2. Right front door rotary tumbler microswitch (M14/5s1)
3. Left front door rotary tumbler microswitch (M14/6s1)
4. Left rear door rotary tumbler microswitch (M14/8s1)
5. Right rear door rotary tumbler microswitch (M14/9s1)
6. Left vent window motor (M21/8) (on model 164.8 and on model 251.0/1 with code (848) Power side vent windows)
7. Right vent window motor (M21/9) (on model 164.8 and on model 251.0/1 with code (848) Power side vent windows)

By the left front door control unit (N69/1), right front door control unit (N69/2) and front SAM control unit (N10)

1. Window position

From the overhead control panel control unit (N70)

1. Tilting/sliding roof position (with code (414) Electric glass tilting/sliding roof)
2. Panoramic roof position (with code (413) Panoramic glass sunroof with top sliding sunroof)

From the electronic ignition switch control unit (N73)

1. Terminal 15

By the central gateway control unit (N93)

1. Coolant temperature sensor (B11/4)
2. Engine speed

Evaluation of input factors

The input factors that have been read in are evaluated by the integrated microprocessor and the affected components are then actuated.

Actuation of components

Components are actuated with the following lines

1. Direct line
2. Climate control LIN
3. Interior CAN

Direct line

The following components are actuated

1. Control valve of the refrigerant compressor (not on model 164.195)
2. Coolant circulation pump (M13)
3. High-voltage battery cooling system shutoff valve (Y19/1) (on model 164.195)
4. Front evaporator shutoff valve (Y19/3) (on model 164.195)

Climate control LIN

The following components are actuated via climate control LIN

1. Blower regulator (A32n1)
2. Fresh air/air recirculation flaps actuator motor (M2/5)
3. Left blend air flap actuator motor (M2/6)
4. Right blend air flap actuator motor (M2/7)
5. Rear shutoff flap actuator motor (M2/12)
6. Footwell flap actuator motors left and right (M2/15)
7. Defroster vent flap actuator motors left and right (M2/16)
8. Rear air distribution flap actuator motor (M2/21)
9. Center air outlet flap actuator motor (M2/22)
10. PTC heater booster (R22/3) (with diesel engine)

Interior CAN

The following components are actuated with the interior CAN: By the rear SAM control unit

1. Rear window defroster

By the central gateway control unit

1. AAC with integrated control additional fan motor (M4/7)

From the left front door control unit

1. Left front power window motor (M10/3)

From the right front door control unit

1. Right front power window motor (M10/4)

By the front SAM control unit

1. Left rear power window motor (M10/5)
2. Right rear power window motor (M10/6)

By the rear SAM control unit on model 164.8 and model 251.0/1 with code (848) Electric side vent window

1. Left vent window motor
2. Right vent window motor

By the overhead control panel control unit with code (414) Power glass tilting/sliding sunroof

1. SR motor (M12m1)

For code (413) Panoramic glass roof with top sliding roof

1. Roller sun blind drive unit (M12/5)
2. Panoramic sliding sunroof drive unit 1 (M12/6)
3. Panoramic sliding sunroof drive unit 2 (M12/7)

On model 164.195

via the central gateway control unit and via engine compartment CAN (CAN C)

1. Electric refrigerant compressor control unit

Wiring diagram for automatic air conditioning (AAC) control unit Model 164 PE83.40-P-2101-97MAA Model 251 PE83.40-P-2101-97RAA

Automatic air conditioning pushbutton control unit, component description - GF83.40-P-3000RT

MODEL 251 with CODE (580) Automatic air conditioning except CODE (494) USA version up to Model Year 8

Scheme 165

Location

The AAC control and operating unit is located on the instrument panel.

Design

The AAC control and operating unit contains the following controls and displays

1. Temperature adjusting ring for driver-side (1)
2. Automatic button (2)
3. Window defrost button (3)
4. Increase air volume button (4)
5. Headroom air distribution button (5)
6. Rear button (6)
7. Passenger side temperature dial (7)
8. AC OFF REST button (8)
9. Center air distribution button (9)
10. Footwell air distribution button (10)
11. Air volume indicator (11)
12. Reduce air volume button (12)
13. Heated rear window switch (N22s1)
14. Air recirculation switch (N22s2)
15. In-car temperature sensor (N22b1)
16. OFF button (13)

The AAC control and operating unit allows the following control actuations

1. Switching the air conditioning system on and off
2. Interior compartment temperature selection cold/warm separate for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Air recirculation mode
7. Defrost function
8. Rear window heater
9. Residual engine heat utilization system

The AAC control and operating unit takes over control of the following

Discreet

1. Coolant circulation pump (M13)
2. Refrigerant compressor (A9)

Via the Controller Area Network bus class B (interior) (CAN-B)

1. Heated rear window (R1) via rear SAM control module (N10/8)
2. Engine and A/C electric suction fan with integrated control (M4/7) via the central gateway control unit (N93) on the ME control unit N3/10)
3. Recirculated air operation for windows and tilting/sliding roof (left front door control unit (N69/1), right front door control unit (N69/2), front SAM control unit (N10), rear SAM control unit, and overhead control panel control unit (N70))

Via Local Interconnect Network (LIN)

1. Blower regulator (A32n1)
2. Fresh air flap/recirculated air flap actuator motor (M2/5)
3. Left blending air flap actuator motor (M2/6)
4. Right blending air flap actuator (M2/7) Rear shutoff flap actuator motor (M2/12)
5. Footwell flap actuator motors left and right (M2/15)
6. Defroster vent flap actuator motors left and right (M2/16)
7. Rear air distribution flap actuator motor (M2/21)
8. Center outlet flap actuator motor (M2/22)

The following sensor signals are read in by the AAC control and operating unit

1. In-car temperature sensor
2. Evaporator temperature sensor (B10/6)
3. Center rear interior temperature sensor (B10/7)
4. Sun sensor (B32)
5. Left side outlet temperature sensor (B10/31)
6. Right side outlet temperature sensor (B10/32)
7. Left center outlet temperature sensor (B10/33)
8. Right center outlet temperature sensor (B10/34)
9. Left footwell temperature sensor (B10/35)
10. Right footwell temperature sensor (B10/36)
11. Outside temperature indicator temperature sensor (B14)
12. Refrigerant pressure sensor (B12)
13. Emissions sensor (B31)

Via CAN B

1. Overhead control panel control unit Rain/light sensor (B38/2)
2. EIS control unit (N73) Circuit status
3. Central gateway control unit and via ME control unit Motor speed Coolant temperature sensor (B11/4)
4. Instrument cluster (A1) Vehicle speed C. 58d
5. Left front door control unit, right front door control unit and front SAM control unit Position of side windows
6. Rear SAM control unit Status of rotary tumbler in doors
7. Overhead control panel control unit Position of tilting/sliding roof Position of panoramic sliding roof

Control possibilities

Left temperature thumb wheel/right temperature thumb wheel

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel.

Air distribution buttons

The air distribution can be controlled in the individual areas by actuating the corresponding button.

Increase air volume button/Decrease air volume button

The air volume can be selected manually by actuating the appropriate button.

Air volume indicator

Indication is accomplished by LEDs coming on. The more LEDs that are illuminated, the greater the air volume flowing into the vehicle interior.

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

OFF button

The automatic air conditioning (AAC) can be switched off completely or switched back on by pressing the OFF button. The main air flap is closed or opened accordingly.

AC OFF REST button

Pressing the AC OFF REST button means that the vehicle can be heated or ventilated only for 30 min. The function can only be used with "circuit 15 OFF". If there is low voltage, the residual heat function is automatically switched off. The flaps are in automatic mode. The blower operates at a set fixed value. When the residua heat mode is activated, the indicator LED comes on.

AC OFF REST button

Pressing the AC OFF REST button switches off the refrigerant compressor. All other functions are retained. When the refrigerant compressor is switched off, the indicator LED comes on.

Heated rear window switch

Once the button has been pressed, the AAC [K-KLA] control and operating unit sends a switch-on request over CAN-B to the rear SAM control unit, while at the same time the function LED in the heated rear window switch is switched on.

Air recirculation switch

When the air recirculation switch is pressed momentarily (t < 1.5 s), the main air flap is closed to prevent air entering from outside. The function LED is illuminated during operation. When pressed for a longer period (t > 1.5 s), the convenience open/close window and tilting/sliding roof (SR) (on vehicles with power glass tilting/sliding roof, code 414) function is activated.

Window defrost button

The temperature is set to "maximum" and the air flow is distributed to the defroster and lateral nozzles. All the other flaps are closed. The blower is controlled depending on the coolant temperature. The indicator LED in the defrost button comes on.

Automatic air conditioning pushbutton control unit, component description - GF83.40-P-3000RTU

MODEL 251.1 with CODE (580) Automatic air conditioning with CODE (494) USA version up to Model Year 8

Exemplified on model series 164

Scheme 166

Location

The AAC control and operating unit is located on the instrument panel.

Design

The AAC control and operating unit contains the following controls and displays

1. Temperature adjusting ring for driver-side (1)
2. Automatic button (2)
3. Window defrost button (3)
4. Increase air volume button (4)
5. Headroom air distribution button (5)
6. REAR OFF button (6)
7. Passenger side temperature dial (7)
8. A/C OFF REST button (8)
9. Center air distribution button (9)
10. Footwell air distribution button (10)
11. Air volume indicator (11)
12. Reduce air volume button (12)
13. Heated rear window switch (N22s1)
14. Air recirculation switch (N22s2)
15. In-car temperature sensor (N22b1)
16. OFF button (14)

The AAC control and operating unit allows the following control actuations

1. Switching the air conditioning system on and off
2. Interior compartment temperature selection cold/warm separate for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Air recirculation mode
7. Defrost function
8. Rear window heater
9. Residual engine heat utilization system

The AAC control and operating unit takes over control of the following

Discreet

1. Coolant circulation pump (M13)
2. Refrigerant compressor (A9)

Via the Controller Area Network bus class B (interior) (CAN-B)

1. Heated rear window (R1) via rear SAM control module (N10/8)
2. Engine and A/C electric suction fan with integrated control (M4/7) via the central gateway control unit (N93) on the ME control unit N3/10)

Via Local Interconnect Network (LIN)

1. Blower regulator (A32n1)
2. Fresh air flap/recirculated air flap actuator motor (M2/5)
3. Left blending air flap actuator motor (M2/6)
4. Right blending air flap actuator (M2/7)
5. Rear shutoff flap actuator motor (M2/12)
6. Footwell flap actuator motors left and right (M2/15)
7. Defroster vent flap actuator motors left and right (M2/16)
8. Rear air distribution flap actuator motor (M2/21)
9. Center outlet flap actuator motor (M2/22)
10. Recirculated air operation for windows and tilting/sliding roof (left front door control unit (N69/1), right front door control unit (N69/2), front SAM control unit (N10), rear SAM control unit, and overhead control panel control unit (N70))

The following sensor signals are read in by the AAC control and operating unit

1. In-car temperature sensor (N22b1)
2. Evaporator temperature sensor (B10/6)
3. Center rear interior temperature sensor (B10/7)
4. Sun sensor (B32)
5. Left side outlet temperature sensor (B10/31)
6. Right side outlet temperature sensor (B10/32)
7. Left center outlet temperature sensor (B10/33)
8. Right center outlet temperature sensor (B10/34)
9. Left footwell temperature sensor (B10/35)
10. Right footwell temperature sensor (B10/36)
11. Outside temperature indicator temperature sensor (B14)
12. Refrigerant pressure sensor (B12)
13. Emissions sensor (B31)

Via CAN B

1. Overhead control panel control unit Rain/light sensor (B38/2)
2. EIS control unit (N73) Circuit status
3. Central gateway control unit and via ME control unit Motor speed Coolant temperature sensor (B11/4)
4. Instrument cluster (A1) Vehicle speed C. 58d
5. Left front door control unit, right front door control unit and front SAM control unit Position of side windows
6. Rear SAM control unit Status of rotary tumbler in doors
7. Overhead control panel control unit Position of tilting/sliding roof Position of panoramic sliding roof

Control possibilities

Left temperature thumb wheel/right temperature thumb wheel

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel.

Air distribution buttons

The air distribution into the individual areas can be controlled by pressing the particular button.

Increase air volume button/Decrease air volume button

The air volume can be selected manually by actuating the appropriate button.

Air volume indicator

Indication is accomplished by LEDs coming on. The more LEDs illuminated, the greater the air volume flowing into the vehicle interior.

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

OFF button

The automatic air conditioning (AAC) can be switched off completely or switched back on by pressing the OFF button. The main air flap is closed or opened accordingly.

A/C OFF REST button

The vehicle can be heated or ventilated only for up to 30 min by pressing the residual heat button. The function is only possible with circuit 15 off or circuit 15C on. If there is low voltage, the residual heat function is automatically switched off. The flaps are in automatic mode. The blower operates at a set fixed value. When the residua heat mode is activated, the indicator LED comes on.

A/C OFF REST button

Pressing the A/C OFF REST button switches off the refrigerant compressor. All other functions are retained. When the refrigerant compressor is switched off, the function LED illuminates.

Heated rear window switch

Once the button has been pressed, the C-AAC [K-KLA] control and operating unit sends a switch-on request over CAN-B to the rear SAM control unit, while at the same time the function LED in the heated rear window switch is switched on.

Air recirculation switch

When the air recirculation switch is pressed momentarily (t < 1.5 s), the main air flap is closed to prevent air entering from outside. The function LED is illuminated during operation. When pressed for a longer period (t > 1.5 s), the convenience open/close window and tilting/sliding roof (SR) (on vehicles with power glass tilting/sliding roof, code 414) function is activated.

Window defrost button

The temperature is set to "maximum" and the air flow is distributed to the defroster and lateral nozzles. All the other flaps are closed. The blower is controlled depending on the coolant temperature. The indicator LED in the defrost button comes on.

Comfort automatic air conditioning control and operating unit, component description - GF83.40-P-3010GM

MODEL 164.1 as of model year 2009 with CODE (581) Comfort automatic air conditioning/YoM 08 model refinement package

MODEL 164.8,251.0/1 as of model year 2009 with CODE (581) Comfort automatic air conditioning/YoM 08

Shown on model 251 without code (494) USA version

Scheme 167

Location

The control and operating unit is located in the center console.

Shown on model 251 with code (494) USA version

Scheme 168

Location

The control and operating unit is located in the center console.

Design

1. Display (14) (without code (494) USA version)

The control and operating unit contains the following controls and displays

1. Left temperature selector wheel (1)
2. "AUTO" button (2)
3. "Defrost" button (3)
4. Increase air volume button (4)
5. Windshield air distribution button (5) (with code (494) USA version) or Right windshield air distribution button (5) (without code (494) USA version)
6. "A/C", "REST" button (6)
7. Right temperature selector wheel (7)
8. "REAR" button (8)
9. Button for air distribution, center right (9)
10. Button for air distribution in right footwell (10)
11. Air volume display (11) (with code (494) USA version)
12. Reduce air volume button (12)
13. "OFF" button (13)
14. Left windshield air distribution button (15) (without code (494) USA version)
15. Center left air distribution button (16) (without code (494) USA version)
16. Left footwell air distribution button (17) (without code (494) USA version)
17. "MONO" button (18) (without code (494) USA version)
18. In-car temperature sensor (N22/7b1)
19. Heated rear window switch (N22/7s1)
20. Air recirculation switch (N22/7s2)

Task

The control and operating unit has the following tasks

1. Operation of the vehicle's climate control
2. Reading in of sensors and signals
3. Evaluation of input factors
4. Actuation of components

Operation of the vehicle's climate control

The control and operating unit enables the following operations

1. Switching the automatic air conditioning on and off
2. Interior temperature selection separated for the left and right side
3. Manual blower control and air distribution
4. Automatic blower control and air distribution
5. Defrost function
6. Residual heat utilization
7. Recirculated air mode
8. Heated rear window (R1) actuation
9. Mono mode (without code (494) USA version)
10. Remote control for rear air conditioning (with code (582) Rear air conditioning)

It is operated with the following controls

1. Temperature selector wheels
2. "AUTO" button
3. Defrosting button
4. Air volume buttons
5. Air distribution buttons
6. "A/C", "REST" button
7. "REAR" button
8. "OFF" button
9. Heated rear window switch
10. Air recirculation switch
11. "MONO" button (without code (494) USA version)

Temperature selector wheels

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel. The selected specified temperature is displayed via LEDs at the border of the temperature selector wheel.

"AUTO" button

The air volume and the air distribution are regulated automatically when the AUTO button is pressed. If the automatic operation is activated, the LED in the "AUTO" button lights up.

The blower level on the USA version is higher than on the Economic Commission for Europe (ECE) version

Defrosting button

Pressing the defroster button sets the temperature to "maximum" and the air flow is distributed to the defroster and side air vents. All the other flaps are closed. The blower output is regulated to match the coolant temperature.

If the function is activated, the light emitting diode in the defroster button illuminates.

Air volume buttons

Pressing the respective air volume button enables the air volume delivered to the interior to be set manually.

The selected setting is displayed in the air volume display (with code (494) USA version) or in the display (without code (494) USA version).

Air distribution buttons

Pressing the respective air distribution button enables the distribution of the air flowing into the interior to be set manually.

If the function is activated, the LED in the respective air distribution button lights up.

"A/C", "REST" button

With circuit 15 ON, press the "A/C", "REST" button to switch the refrigerant compressor (A9) (not on model 164.195) or the electric refrigerant compressor control unit (N19/4) (on model 164.195) on or off. All other functions are retained.

The LED in the "A/C", "REST" button lights up with the refrigerant compressor switched on.

With circuit 15C or circuit 15R, the residual engine heat utilization system function is activated by pressing the "A/C", "REST" button. When the function is activated, the LED illuminates.

"REAR" button

The "REAR" button can be used to change the rear temperature values via the control and operating unit. When the "REAR" button is pressed, the specified rear temperature values appear in the right temperature selector wheel. The blower setting is not visible.

Without code (494) USA version, the letters REAR appear in the display when the function is active

The function is stopped automatically if operation is not performed within approx. t = 5 s or the "REAR" button is pressed again. During operation with the remote control, an adjustment of the specified values in the rear is not possible.

The rear values are stored in the control and operating unit.

With code (494) USA version, the "REAR" button is provided with the lettering REAR instead of a pictogram

"OFF" button

The automatic air conditioning can be switched off completely or switched back on by pressing the "OFF" button.

The LED in the "OFF" button lights up when the automatic air conditioning is switched off.

Rear window heater switch

The rear window heater is switched on when the rear window heater switch is pressed. The LED lights up during operation of the rear window heater.

The operating time of the rear window heater is calculated by the rear SAM control unit (N10/8) depending on the outside temperature and the vehicle speed

Air recirculation switch

When the air recirculation switch on the control and operating unit is pressed for t < 1.5 s, the fresh air/air recirculation flap is closed, and thus the supply of outside air is prevented. The air only circulates in the vehicle interior and unpleasant odors and harmful gases are kept out. The LED in the air recirculation switch comes on.

Pressing the air recirculation switch for t > 1.5 s activates comfort recirculation closing. In the process the windows, the tilting/sliding roof (with code (414) Power glass tilting/sliding roof) or the panoramic sunroof (model 251 with code (413) Panoramic glass sunroof with top sliding sunroof) and the vent windows (model 164.8 and model 251 with code (848) Power side vent windows) are closed automatically. When the air recirculation switch is pressed again for t > 1.5 s, the windows, the tilting/sliding roof or the panoramic sunroof and the vent windows return to the previous positions.

With code (460) Canada version and code (494) USA version, convenience recirculation closing is not possible

The detailed convenience recirculation closing procedure is described in the convenience feature function (KFB)

"MONO" button

When the "MONO" button is pressed, the air distribution and temperature values set on the driver side are adopted for the passenger side.

Reading in of sensors and signals

The input factors are read in with the following connections

1. Direct line
2. Climate control LIN
3. Interior CAN

Direct line

The following sensors are read in via a direct line

1. Interior air temperature sensor
2. Evaporator temperature sensor (B10/6)
3. Center rear interior temperature sensor (B10/7)
4. Left side outlet temperature sensor (B10/31)
5. Right side outlet temperature sensor (B10/32)
6. Left center outlet temperature sensor (B10/33)
7. Right center outlet temperature sensor (B10/34)
8. Left footwell temperature sensor (B10/35)
9. Right footwell temperature sensor (B10/36)
10. Rear headroom AC temperature sensor (B10/37) (with code (582) Rear air conditioning)
11. Refrigerant pressure sensor (B12)
12. Outside temperature indicator temperature sensor (B14)
13. Emissions sensor (B31)
14. Dual sun sensor (B32/3)

Climate control LIN

The following sensor is read in via climate control LIN

1. Dew point sensor (B11/12)

Interior CAN

The following signals and sensors are read in via interior CAN: By the instrument cluster (A1)

1. Ground speed

By the rear SAM control unit

1. Rear door locking unit (A72)
2. Right front door rotary tumbler microswitch (M14/5s1)
3. Left front door rotary tumbler microswitch (M14/6s1)
4. Left rear door rotary tumbler microswitch (M14/8s1)
5. Right rear door rotary tumbler microswitch (M14/9s1)
6. Left vent window motor (M21/8) (on model 164.8 and on model 251.0/1 with code (848) Power side vent windows)
7. Right vent window motor (M21/9) (on model 164.8 and on model 251.0/1 with code (848) Power side vent windows)

By the left front door control unit (N69/1), right front door control unit (N69/2) and front SAM control unit (N10)

1. Window position

From the overhead control panel control unit (N70)

1. Position of the tilting/sliding roof
2. Position of the panoramic sunroof

From the electronic ignition switch control unit (N73)

1. Terminal 15

By the central gateway control unit (N93)

1. Coolant temperature sensor (B11/4)
2. Engine speed

Evaluation of input factors

The input factors that have been read in are evaluated by the integrated microprocessor and the affected components are then actuated.

Actuation of components

The actuation of the components takes place via the following connections

1. Direct line
2. Climate control LIN
3. Interior CAN

Direct line

The following components are actuated

1. Control valve of the refrigerant compressor (not on model 164.195)
2. Coolant circulation pump (M13)
3. Booster blower electronic blower regulator (N29/2) (without code (582) Rear air conditioning)
4. High-voltage battery cooling system shutoff valve (Y19/1) (on model 164.195)
5. Front evaporator shutoff valve (Y19/3) (on model 164.195)

Climate control LIN

The following components are actuated via climate control LIN

1. Blower regulator (A32n1)
2. Fresh air/air recirculation flaps actuator motor (M2/5)
3. Left blend air flap actuator motor (M2/6)
4. Right blend air flap actuator motor (M2/7)
5. Left defroster vent flap actuator motor (M2/8)
6. Right defroster vent flap actuator motor (M2/9)
7. Left footwell flap actuator motor (M2/10)
8. Right footwell flap actuator motor (M2/11)
9. Rear shutoff flap actuator motor (M2/12)
10. Rear air distribution flap actuator motor (M2/21)
11. Left center air flap actuator motor (M16/23)
12. Right center air flap actuator motor (M16/24)
13. Rear air conditioning blower regulator (N29/7) (with code (582) Rear air conditioning)
14. PTC heater booster (R22/3) (with diesel engine)

Interior CAN

The following components are actuated with the interior CAN: By the rear SAM control unit

1. Rear window defroster

By the central gateway control unit

1. AAC with integrated control additional fan motor (M4/7)

From the left front door control unit

1. Left front power window motor (M10/3)

From the right front door control unit

1. Right front power window motor (M10/4)

By the front SAM control unit

1. Left rear power window motor (M10/5)
2. Right rear power window motor (M10/6)

By the rear SAM control unit on model 164.8 and on model 251.0/1 with code (848) Power side vent windows

1. Left vent window motor
2. Right vent window motor

By the overhead control panel control unit with code (414) Power glass tilting/sliding sunroof

1. SR motor (M12m1)

For code (413) Panoramic glass roof with top sliding roof

1. Roller sun blind drive unit (M12/5)
2. Panoramic sliding sunroof drive unit 1 (M12/6)
3. Panoramic sliding sunroof drive unit 2 (M12/7)

On model 164.195

via the central gateway control unit and via engine compartment CAN (CAN C)

1. Electric refrigerant compressor control unit

Comfort automatic air conditioning control and operating unit, component description - GF83.40-P-3010RT

MODEL 251 with CODE (581) Comfort automatic air conditioning except CODE (494) USA version with CODE (582) Rear air conditioner up to Model Year 8

Scheme 169

Location

The comfort AAC control and operating unit is located in the instrument panel.

Design

The comfort automatic air conditioning control and operating unit includes the following controls and display elements

1. Driver side temperature dial (1)
2. Automatic button (2)
3. Button for air distribution in left head area (3)
4. Window defrost button (4)
5. Increase air volume button (5)
6. Heated rear window switch (N22/7s1)
7. Button for air distribution in right head area (6)
8. Rear button (7)
9. Passenger side temperature dial (8)
10. OFF/REST button (9)
11. Button for air distribution in right footwell (10)
12. Button for air distribution, center right (11)
13. AC OFF REST button (12)
14. Display (13)
15. Button for decreasing the air flow (14)
16. Air recirculation switch (N22/7s2)
17. Button for air distribution, center left (15)
18. Button for air distribution in left footwell (16)
19. In-car temperature sensor (N22/7b1)
20. MONO button (17)

The AAC control and operating unit is used to control the following

1. Switching the air conditioning system on and off
2. Cold/warm interior temperature programming for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Air recirculation mode
7. Defrost function
8. Rear window heater
9. Residual engine heat utilization system
10. Option for coupling the front passenger temperature selection with that of the driver-side
11. Remote control for rear air conditioning

The comfort automatic air conditioning control and operating unit is used to actuate the following

Discreet

1. Coolant circulation pump (M13)
2. Refrigerant compressor (A9)

Via the Control Area Network bus, class B (interior compartment) (CAN B)

1. Heated rear window (R1) via rear SAM control unit (N10/8)
2. Engine and A/C electric suction fan with integrated control (M4/7) via the central gateway control unit (N93) on the ME control unit N3/10)
3. Recirculated air operation for windows and tilting/sliding roof (left front door control unit (N69/1), right front door control unit (N69/2), front SAM control unit (N10), rear SAM control unit, and overhead control panel control unit (N70))

Via Local Interconnect Network (LIN)

1. Blower regulator (A32n1)
2. Fresh air flap/recirculated air flap actuator motor (M2/5)
3. Left blend air flap actuator (M2/6)
4. Right blend air flap actuator (M2/7)
5. Left defroster vent flap actuator motor (M2/8)
6. Right defroster vent flap actuator motor (M2/9)
7. Left footwell flap actuator motor (M2/10)
8. Right footwell flap actuator motor (M2/11)
9. Rear shutoff flap actuator motor (M2/12)
10. Rear air distribution flap actuator motor (M2/21)
11. Left center air flap actuator motor (M16/23)
12. Right center air flap actuator motor (M16/24)
13. Diverter flap actuator motor (M16/27)

The comfort automatic air conditioning control and operating unit reads in the following sensor signals

1. In-car temperature sensor
2. Refrigerant pressure sensor (B12)
3. Evaporator temperature sensor (B10/6)
4. Dual sun sensor (B32/3)
5. Left side outlet temperature sensor (B10/31)
6. Right side outlet temperature sensor (B10/32)
7. Left center outlet temperature sensor (B10/33)
8. Right center outlet temperature sensor (B10/34)
9. Left footwell temperature sensor (B10/35)
10. Right footwell temperature sensor (B10/36)
11. Outside temperature indicator temperature sensor (B14)
12. Dew point sensor (B11/12)
13. Emissions sensor (B31)

Via CAN B

1. Overhead control panel control unit Rain/light sensor (B38/2)
2. EIS control unit (N73) Circuit status
3. Central gateway control unit and via ME control unit Motor speed Coolant temperature sensor (B11/4)
4. Instrument cluster (A1) Vehicle speed C. 58d
5. Left front door control unit, right front door control unit and front SAM control unit Position of side windows
6. Rear SAM control unit Status of rotary tumbler in doors
7. Overhead control panel control unit Position of tilting/sliding roof

Control possibilities

Left temperature selector wheel/right temperature selector wheel

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel.

Air distribution buttons

The air distribution into the individual areas can be controlled by pressing the particular button.

Increase air volume button/Decrease air volume button

The air volume can be selected manually by actuating the appropriate button.

Display

The blower power or the active or inactive REAR function is shown in the display. In the event of maximum cooling capacity, "MAX COOL" is additionally shown in the USA version.

Automatic button

When the AUTO button is actuated, the AUTO mode is activated and the red LED in the AUTO button comes on. In automatic mode, temperature control the blower output and air distribution are controlled automatically, in addition to temperature control. Manually resetting the blower or the air distribution, terminates the AUTO mode. When the vehicle is restarted, the function last set is activated.

OFF button

The comfort automatic air conditioning (C-AAC [K-KLA]) can be switched off completely and switched on again by pressing the OFF button. The main air flap is closed or opened accordingly.

Mono button

The settings on the driver's side are taken over for the other temperature zones with the aid of the MONO button. The corresponding setting is indicated by a red LED display. The function can be deactivated by pressing the MONO button again or manually changing the values for the other temperature zones.

REST button

The vehicle can be heated or ventilated only for up to 30 min by pressing the residual heat button. The function is only possible with circuit 15 off or circuit 15C on. If there is low voltage, the residual heat function is automatically switched off. The flaps are in automatic mode. The blower operates at a set fixed value. When the residua heat mode is activated, the indicator LED comes on.

AC-OFF button

Pressing the AC-OFF button switches off the refrigerant compressor. All other functions are retained. When the refrigerant compressor is switched off, the indicator LED comes on.

Rear button

The REAR button can be used to change the rear temperature values using the comfort AAC [KLA] control and operating unit. When the rear button is pressed, the specified rear temperature values appear in the right temperature selector wheel. The blower setting is not visible.

Air recirculation switch

A brief press (t < 1.5 s) of the air recirculation switch shuts down the main air flap. The function LED is illuminated during operation. When pressed for a longer period (t > 1.5 s), the convenience open/close window and tilting/sliding roof (SR) (on vehicles with power glass tilting/sliding roof, code 414) function is activated.

Heated rear window switch

When the button is pressed, the comfort automatic air conditioning control and operating unit transmits a switch-on request via CAN-B to the rear SAM control unit, and the function LED in the heated rear window switch comes on at the same time.

Window defrost button

The temperature is set to "maximum" and the air flow distributed to the defroster and lateral nozzles. All the other flaps are closed. The blower is controlled depending on the coolant temperature. The indicator LED in the defrost button comes on.

1. Remote control for rear AC functions

When the REAR button on the comfort AAC control and operating unit (N22/7) is pressed, the operating unit symbol appears in the front display. The blower setting is not visible. The rear temperatures can be set on the keyboard. The function is stopped automatically, if operation is not performed within approx. t = 5 s or the REAR button is pressed again. When the AUTO button or the REAR Button is pressed, the REAR operation can be stopped.

Comfort automatic air conditioning control and operating unit, component description - GF83.40-P-3010RTU

MODEL 251.1 with CODE (581) Comfort automatic air conditioning with CODE (494) USA version with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (494) USA version with CODE (582) Rear air conditioner up to Model Year 8

Shown on model series 251.1

Scheme 170

Location

The comfort AAC control and operating unit is located in the instrument panel.

Design

The comfort AAC control and operating unit contains the following controls and displays

1. Driver side temperature dial (1)
2. Automatic button (2)
3. Button for air distribution in left head area (3)
4. Window defrost button (4)
5. Increase air volume button (5)
6. Heated rear window switch (N22/7s1)
7. Button for air distribution in right head area (6)
8. REAR button (7)
9. Passenger side temperature dial (8)
10. OFF button (9)
11. Button for air distribution in right footwell (10)
12. Button for air distribution, center right (11)
13. AC-OFF Rest button (12)
14. Display (13)
15. Button for decreasing the air flow (14)
16. Air recirculation switch (N22/7s2)
17. Button for air distribution, center left (15)
18. Button for air distribution in left footwell (16)
19. In-car temperature sensor (N22/7b1)
20. MONO button (17)

The AAC control and operating unit is used to control the following

1. Switching the air conditioning system on and off
2. Cold/warm interior temperature programming separately for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Air recirculation mode
7. Defrost function
8. Rear window heater
9. Residual engine heat utilization system
10. Option for coupling the front passenger temperature selection with that of the driver-side
11. Rear air conditioner remote control

The comfort AAC control and operating unit is used to actuate the following

Discreet

1. Refrigerant compressor (A9)
2. Coolant circulation pump (M13)
3. Rear AC additional circulation pump (M13/1)
4. Coolant shutoff motor (M16/41)
5. Rear air conditioning blower regulator (N29/7)
6. AC system shutoff valve (Y19/1)

Via the Control Area Network bus, class B (interior compartment) (CAN B)

1. Heated rear window (R1) via rear SAM control unit (N10/8)
2. Engine and A/C electric suction fan with integrated control (M4/7) via the central gateway control unit (N93) on the ME control unit N3/10)
3. Recirculated air operation for windows and tilting/sliding roof (left front door control unit (N69/1), right front door control unit (N69/2), front SAM control unit (N10), rear SAM control unit, and overhead control panel control unit (N70))

Via Local Interconnect Network (LIN)

1. Blower regulator (A32n1)
2. Rear air conditioning blower regulator
3. Dew point sensor (B11/12)
4. Fresh air flap/recirculated air flap actuator motor (M2/5)
5. Left blend air flap actuator (M2/6)
6. Right blend air flap actuator (M2/7)
7. Left defroster vent flap actuator motor (M2/8)
8. Right defroster vent flap actuator motor (M2/9)
9. Left footwell flap actuator motor (M2/10)
10. Right footwell flap actuator motor (M2/11)
11. Rear shutoff flap actuator motor (M2/12)
12. Rear air distribution flap actuator motor (M2/21)
13. Left center air flap actuator motor (M16/23)
14. Right center air flap actuator motor (M16/24)
15. Diverter flap actuator motor (M16/27)
16. 3rd seat row air distribution actuator motor (M16/43)
17. 3rd seat row blend air flap actuator motor (M16/44)

The following sensor signals are read in by the comfort AAC control and operating unit

1. In-car temperature sensor (N22b1)
2. Refrigerant pressure sensor (B12)
3. Evaporator temperature sensor (B10/6)
4. Rear air conditioning evaporator temperature sensor (B10/11)
5. Dual sun sensor (B32/3)
6. Center rear interior temperature sensor (B10/7)
7. Left side outlet temperature sensor (B10/31)
8. Right side outlet temperature sensor (B10/32)
9. Left center outlet temperature sensor (B10/33)
10. Right center outlet temperature sensor (B10/34)
11. Left footwell temperature sensor (B10/35)
12. Right footwell temperature sensor (B10/36)
13. Rear headroom AC temperature sensor (B10/37)
14. Footwell rear AC temperature sensor (B10/38)
15. Outside temperature indicator temperature sensor (B14)
16. Emissions sensor (B31)

Via LIN bus: dew point sensor (B11/12)

Via CAN B

1. Overhead control panel control unit Rain/light sensor (B38/2)
2. EIS control unit (N73) Circuit status
3. Central gateway control unit and via ME control unit Motor speed Coolant temperature sensor (B11/4)
4. Instrument cluster (A1) Vehicle speed C. 58d
5. Left front door control unit, right front door control unit and front SAM control unit Position of side windows
6. Rear SAM control unit Status of the rotary tumblers in the doors Position of the pop-out windows
7. Overhead control panel control unit Position of the tilting/sliding roof Position of the panoramic sliding roof

Control possibilities

Left temperature selector wheel/right temperature selector wheel

The desired temperature setting for the left and right sides can be set by turning the associated temperature selector wheel.

Air distribution buttons

The air distribution into the individual areas can be controlled by pressing the particular button.

Increase air volume button/Decrease air volume button

The air volume can be selected manually by actuating the appropriate button.

Display

The blower power or the active or inactive REAR function is shown in the display. "MAX COOL" is also displayed at maximum cooling power.

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

OFF button

The comfort automatic air conditioning (C-AAC [K-KLA]) can be switched off completely and switched on again by pressing the OFF button. The main air flap is closed or opened accordingly.

1. Remote control for rear AC functions

When the REAR button on the comfort AAC control and operating unit (N22/7) is pressed, the operating unit symbol appears in the front display. The blower setting is not visible. The rear temperatures can be set on the keyboard. The function is stopped automatically, if operation is not performed within approx. t = 5 s or the REAR button is pressed again. When the AUTO button or the REAR Button is pressed, the REAR operation can be stopped.

REST button

The vehicle can be heated or ventilated only for up to 30 min by pressing the residual heat button. The function is only possible with circuit 15 off or circuit 15C on. If there is low voltage, the residual heat function is automatically switched off. The flaps are in automatic mode. The blower operates at a set fixed value. When the residua heat mode is activated, the indicator LED comes on.

AC-OFF button

Pressing the AC-OFF button switches off the refrigerant compressor. All other functions are retained. When the refrigerant compressor is switched off, the indicator LED comes on.

REAR button

The REAR button can be used to change the rear temperature values via the comfort AAC control and operating unit. When the rear button is pressed, the specified rear temperature values appear in the right temperature selector wheel. The blower setting is not visible.

Air recirculation switch

When the air recirculation switch is pressed momentarily (t < 1.5 s), the main air flap is closed to prevent air entering from outside. The function LED is illuminated during operation. When pressed for a longer period (t > 1.5 s), the convenience opening/closing of windows and the tilting/sliding roof (on vehicles with power glass tilting/sliding roof, code 414) is activated.

Heated rear window switch

When the button is pressed, the comfort automatic air conditioning control and operating unit transmits a switch-on request via CAN-B to the rear SAM control unit, and the function LED in the heated rear window switch comes on at the same time.

Button for window defrosting

The temperature is set to "maximum" and the air flow distributed to the defroster and lateral nozzles. All the other flaps are closed. The blower is controlled depending on the coolant temperature. The indicator LED in the defrost button comes on.

Rear control panel control unit, component description - GF83.40-P-3020GMA

MODEL 164.1 as of model year 09/YoM model refinement package except CODE (581) Comfort automatic air conditioning

MODEL 164.8,251.0/1 as of model year 09/YoM 08 except CODE (581) Comfort automatic air conditioning

Shown on model 164

Scheme 171

Location

The RCP [HBF] control unit is located in the extension of the center console in the 2nd seat row

Design

The RCP [HBF] control unit includes the following control and display elements

1. AUTO button (1)
2. Headroom air distribution button (2)
3. Footwell air distribution button (3)
4. OFF button (4)

Task

The RCP [HBF] control unit has the following tasks

1. Operation of the rear air conditioning
2. Reading in of signals
3. Actuation of components

Operation of the rear air conditioning

The RCP control unit allows the following actions

1. Switching the temperature control ON and OFF
2. Manual air distribution
3. Automatic blower control and air distribution

It is operated with the following buttons

1. AUTO button
2. Air distribution buttons
3. OFF button

AUTO button

The air volume and the air distribution are regulated automatically when the AUTO button is pressed.

If automatic mode is activated, the LED illuminates.

Air distribution buttons

Pressing the respective air distribution button enables the distribution of the air flowing into the rear area to be set manually. When the function is activated, the LED illuminates.

OFF button

The temperature control in the rear can be switched off completely or switched back on by pressing the OFF button. The rear shut-off flap is opened or closed accordingly.

The LED lights up when the temperature control is switched off.

Reading in of signals

The input factors are read in via the following connection

1. Interior CAN

Interior CAN

The signals are read in by the rear control panel control unit via the interior CAN.

The resulting functions are described in the relevant function descriptions (see block diagram or function schematic).

Actuation of components

The actuation of the components takes place via the following connections

1. Interior CAN

Interior CAN

The signals are transmitted by the rear control panel control unit via the interior CAN. The resulting functions are described in the relevant function descriptions (see block diagram or function schematic).

Rear control panel control unit, component description - GF83.40-P-3020GMB

MODEL 164.1 as of model year 09/YoM 08 model refinement package with CODE (581) Comfort automatic air conditioning

MODEL 164.8,251.0/1 as of model year 09/YoM 08 with CODE (581) Comfort automatic air conditioning

Shown on model 251 without code (494) USA version with code (519) Rear audio system and with code (872) Electric seat heater for left and right rear seats

Scheme 172

Location

The RCP [HBF] control unit is located in the extension of the center console in the 2nd seat row.

Shown on model 251 with code (494) USA version, with code (519) Rear audio system and with code (872) Electric seat heater for left and right rear seats

Scheme 173

Location

The RCP [HBF] control unit is located in the extension of the center console in the 2nd seat row.

Design

The RCP [HBF] control unit includes the following control and display elements

1. Left headphones volume control (1) (with code (519) Rear audio system)
2. Increase air volume button (2)
3. Air volume indicator (3)
4. Temperature selector wheel (4)
5. AUTO button (5)
6. Headroom air distribution button (6)
7. Right headphones volume control (7) (with code (519) Rear audio system)
8. Right headphones connector jack (8) (with code (519) Rear audio system)
9. Footwell air distribution button (9)
10. OFF button (10)
11. Reduce air volume button (11)
12. Left headphones connector jack (12) (with code (519) Rear audio system)
13. Button for seat heater in 2nd seat row, left (13) (with code (872) Electrically heated left and right rear seats)
14. Button for seat heater in 2nd seat row, right (14) (with code (872) Electrically heated left and right rear seats)

Task

The RCP [HBF] control unit has the following tasks

1. Operation of the rear air conditioning
2. Reading in of signals
3. Actuation of components

Operation of the rear air conditioning

The RCP control unit allows the following actions

1. Switching the temperature control ON and OFF
2. Interior temperature selection for the rear area
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Separate left and right headphones volume control (with code (519) Rear audio system)
7. Separately regulated left and right seat heaters (with code (872) Electric seat heater for left and right rear seats)

The cooling and heat output is increased in the rear area by the rear air conditioning (model 164.8 and model 251 with code (582) Rear air conditioning)

It is operated with the following buttons, rotary switches and the selector wheel

1. Temperature selector wheel
2. Air volume buttons
3. AUTO button
4. OFF button
5. Air distribution buttons
6. Headphones volume control (with code (519) Rear audio system)
7. Seat heater buttons (with code (872) Electrically heated left and right rear seats)

Temperature selector wheel

The desired specified temperature for the rear compartment can be set by turning the temperature selector wheel.

The selected specified temperature is displayed via LEDs at the border of the temperature selector wheel.

Air volume buttons

Pressing the respective air volume button enables the volume of air flowing into the rear area to be set manually.

An LED in the air volume display lights up.

Pressing repeatedly permits the air volume that is introduced into the vehicle interior to be increased.

The greater the requested air volume, the more LEDs that light up.

AUTO button

The air volume and the air distribution are regulated automatically when the AUTO button is pressed.

If the automatic operation is activated, the LED in the AUTO button lights up.

OFF button

The temperature control in the rear can be switched off completely or switched back on by pressing the OFF button. The rear shut-off flap is opened or closed accordingly.

The LED lights up when the temperature control is switched off.

Air distribution buttons

Pressing the respective air distribution button enables the distribution of the air flowing into the rear area to be set manually.

When the function is activated, the LED illuminates.

Headphones volume control

The requested volume of the headphones can be selected by turning the particular volume control. The volume can be regulated separately for left and right.

Seat heater buttons

The heat output for the relevant side can be regulated in three stages by pressing the relevant seat heaters button.

The particular button signal is transmitted via interior CAN to the seat heater, seat ventilation and steering wheel heater control unit (N25/7).

Reading in of signals

The input factors are read in with the following connections

1. Direct line
2. Interior CAN

Direct line

The following signals are read in via a direct line

1. Left audio input (with code (519) Rear audio system)
2. Right audio input (with code (519) Rear audio system)

Interior CAN

The signals are read in by the rear control panel control unit via the interior CAN. The resulting functions are described in the relevant function descriptions (see block diagram or function schematic).

Actuation of components

The actuation of the components takes place via the following connections

1. Direct line
2. Interior CAN

Direct line

The following components are actuated

1. Left headphones connector jack (with code (519) Rear audio system)
2. Right headphones connector jack (with code (519) Rear audio system)
3. Left headphones volume control (with code (519) Rear audio system)
4. Right headphones volume control (with code (519) Rear audio system)

Interior CAN

The signals are transmitted by the rear control panel control unit via the interior CAN. The resulting functions are described in the relevant function descriptions (see block diagram or function schematic).

Rear control panel control unit, component description - GF83.40-P-3020RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Exemplified on model series 164

Scheme 174

Location

The RCP [HBF] control unit is positioned in the center console extension in the second row of seats

Design

1. Automatic button (1)
2. Headroom air distribution button (2)
3. Footwell air distribution button (3)
4. OFF button (4)

Discrete inputs

1. Tml. 30
2. (Term. 31)

The RCP control unit is a CAN B bus subscriber.

The RCP control unit allows the following actions

1. Switching the temperature control ON and OFF
2. Manual air distribution
3. Automatic blower control and air distribution

Operating possibilities

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

Air distribution buttons

The air distribution can be controlled in the individual areas by actuating the corresponding button.

OFF button

The temperature control in the rear can be switched off completely or switched back on by pressing the OFF button. The rear shut-off flap is opened or closed accordingly.

Rear control panel control unit, component description - GF83.40-P-3020RTE

MODEL 251 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner with CODE (519) Rear audio system with CODE (872) Electrically heated left and right rear seats up to Model Year 8

Scheme 175

Location

The RCP [HBF] control unit is located in the extension of the center console near the 2nd seat row.

Design

1. Volume control for left headphones (1)
2. Button for increasing the air flow (2)
3. Air volume display (3)
4. Temperature adjusting ring (4)
5. Automatic button (5)
6. Button for air distribution in head area (6)
7. Volume control for right headphones (7)
8. Plug socket for right headphones (8)
9. Button for air distribution in footwell (9)
10. OFF button (10)
11. Button for decreasing the air flow (11)
12. Plug socket for left headphones (12)
13. Heated seats 2nd seat row, left button (13)
14. Heated seats 2nd seat row, right button (14)

The RCP control unit allows the following actions

1. Switching the temperature control ON and OFF
2. Interior compartment temperature selection cold/warm separate for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Volume control of headphones separately for left and right
7. Heated seats can be separately regulated for left and right

Discrete inputs

1. Tml. 30
2. Circuit 31
3. Audio input, left
4. Audio input, right

Discrete outputs

1. Plug socket for left headphones
2. Plug socket for right headphones
3. Volume control for left headphones
4. Volume control for right headphones

The RCP [HBF] control unit is a participant of the CAN-B

Control possibilities

Temperature adjusting ring

The desired specified temperature for the rear compartment can be set by turning the temperature adjusting ring.

Button for increasing the air flow/button for decreasing the air flow

The air volume can be selected manually by actuating the appropriate button.

Air volume indicator

The display is by means of particular LEDs that are coming on. The more LEDs illuminate, the greater the air volume flowing into the vehicle interior.

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

OFF button

The temperature control in the rear can be switched off completely or switched back on by pressing the OFF button.

Air distribution buttons

The air distribution can be controlled in the individual areas by actuating the corresponding button.

Headphones volume control

When the volume control is turned, the volume of the headphones can be selected based on the needs of the rear passenger. The volume can be regulated separately for left and right.

Heated seats button

Pressing the heated seats button enables the heat output for each side to be regulated in three stages.

Each button signal is notified to the HS [SIH], seat ventilation and steering wheel heater control unit (N25/7) via CAN-B from the RCP [HBF] control unit.

Rear control panel control unit, component description - GF83.40-P-3020RTU

MODEL 251.1 with CODE (581) Comfort automatic air conditioning with CODE (494) USA version with CODE (582) Rear air conditioner with CODE (519) Rear audio system with CODE (872) Electrically heated left and right rear seats up to Model Year 8

MODEL 164 with CODE (581) Comfort automatic air conditioning with CODE (494) USA version with CODE (582) Rear air conditioner with CODE (519) Rear audio system with CODE (872) Electrically heated left and right rear seats up to Model Year 8

Scheme 176

Location

The RCP control unit is located next to the 2nd seat row in an extension of the center console.

Design

1. Left headphones volume control (1)
2. Increase air volume button (2)
3. Air volume indicator (3)
4. Temperature dial (4)
5. Automatic button (5)
6. Headroom air distribution button (6)
7. Right headphones volume control (7)
8. Right headphones connecting socket (8)
9. Footwell air distribution button (9)
10. OFF button (10)
11. Reduce air volume button (11)
12. Left headphones connecting socket (12)
13. Heated seats button, 2nd seat row, left (13)
14. Heated seats button, 2nd seat row, right (14)

The RCP control unit allows the following actions

1. Switching the temperature control ON and OFF
2. Warm/cold interior temperature selection, separate for left and right
3. Manual blower control
4. Manual air distribution
5. Automatic blower control and air distribution
6. Headphone volume control, separate for left and right
7. Heated seats, separate controls for left and right

Discrete inputs

1. Circuit 30
2. Circuit 31
3. Left audio input
4. Right audio input

Discrete outputs

1. Left headphone connecting socket
2. Right headphone connecting socket
3. Left headphone volume control
4. Right headphone volume control

The RCP control unit is a CAN B bus subscriber

Operating possibilities

Temperature dial

The required target temperature for the rear compartment can be selected by rotating the temperature dial.

Increase air volume button/Decrease air volume button

The air volume can be selected manually by actuating the appropriate button.

Air volume indicator

The indication is accomplished by illuminating LEDs. The more LEDs illuminate, the greater the air volume flowing into the vehicle interior.

Automatic button

The air volume and air distribution are regulated automatically when the automatic button is pressed. When the automatic mode is activated, the indicator LED comes on.

OFF button

The temperature control in the rear can be switched off completely or switched back on by pressing the OFF button.

Air distribution buttons

The air distribution can be controlled in the individual areas by actuating the corresponding button.

Headphone volume control

The headphone volume that is required by the passenger in the rear can be adjusted by rotating the volume control. The volume can be controlled separately for the right and left.

Heated seats button

The heat output for the relevant side can be regulated in three stages by pressing the heated seats button.

The HS [SIH], seat ventilation and steering wheel heater control unit (N25/7) is notified of the respective button signal via CAN-B by the RCP [HBF] control unit.

Overview of automatic climate control system components - GF83.40-P-9995GM

MODEL 164.1 as of model year 2009/YoM 08 model refinement package

MODEL 164.8, 251.0/1 as of model year 2009/YoM 08

Overview of system components for the comfort automatic air conditioning (C-AAC) - GF83.40-P-9998RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Rear air conditioning housing component description - GF83.50-P-1000RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on model series 251

Scheme 177

Location

The rear air conditioning housing is at the left rear behind the side paneling of the load compartment.

Design

The rear air conditioning housing is designed with the following components

1. Evaporator
2. Rear air conditioning blower motor (M2/29)
3. Rear air conditioning blower regulator (N29/7)
4. Expansion valve
5. 3rd seat row air distribution actuator motor (M16/43)
6. 3rd seat row blend air flap actuator motor (M16/44)

Rear air conditioning normal mode Function

In normal mode when the rear air conditioning is switched off, recirculated air is drawn out of the rear interior by the rear air conditioning blower motor via the rear air inlet into the rear AC housing. The recirculated airflows through the evaporator (not cooled). Then the recirculated air is directed to the air outlets supplied with air via the air distribution flap.

Rear air conditioning cooling mode Function

In cooling mode, when the rear air conditioning is switched on, recirculated air is drawn out of the rear interior by the rear air conditioning blower motor via the rear air inlet into the rear AC housing. The recirculated air enters the cooled evaporator and is cooled down. Next, the dried and cooled air is directed through the unheated heater heat exchanger via the air distribution flap to the air outlets that are supplied with air.

The condensation is led to the outside via the condensation drain.

Component description of refrigerant compressor - GF83.55-P-2108RT

ENGINE 113.971, 272.967 in MODEL 251.1/0 up to Model Year 8

Scheme 178

Location

The refrigerant compressor is connected to the engine at the front left.

Task

The refrigerant compressor is responsible for induction and compression of the refrigerant.

Scheme 179

Design

A total of 7 pistons are distributed around the circumference of the component and connected to the swash plate by sliding shoes to ensure the same pitch. The swash plate is connected to the stop plate in the crankcase by 2 guide pins and mounted on the refrigerant compressor shaft so that it can move.

The stop plate and belt pulley are stuck on the refrigerant compressor shaft. The externally-controlled refrigerant compressor control valve for adjustment of the swash plate is located in the rear section of the housing.

Function

Operating mechanism

The rotary movement of the belt pulley is transmitted over the refrigerant compressor shaft to the stop plate, which is permanently fastened to the refrigerant compressor shaft by way of a press fit. The rotation of the stop plate is then transmitted to the pivoted swash plate by means of a hinged mechanism. The conversion of the swash plate rotary motion into the oscillating piston movement takes place via two sliding shoes between the piston and swash plate. The 7 pistons are connected at the circumference with the swash plate with the same pitch. The evaporation tank on the pressure side and evaporation tank on the suction side reduce gas pulsation in the refrigerant compressor by providing for uniform refrigerant flow. This helps to prevent noises in the compression process

Volume regulation mechanism

The refrigerant compressor delivery rate is regulated by the externally-controlled refrigerant compressor control valve by the regulation flow between 2% (minimum delivery rate) and 100% (maximum delivery rate). The required control flow rate on the refrigerant compressor control valve is set by the AAC control and operating unit (N22) or comfort AAC control and operating unit (N22/7) depending on the required refrigeration capacity. The required refrigeration capacity is determined primarily by the vehicle interior temperature setting. The swash plate position and the variable delivery rate are always determined by the crankcase pressure, the membrane pressure in the refrigerant compressor control valve (approx. 2 bar) and the suction pressure. These pressures are determined on the basis of the sensing, processing and evaluation of the controlled variables in the air conditioning system.

The change in the suction pressure, depending on the control flow on the refrigerant compressor control valve, causes a change in the crankcase pressure and therefore, adjustment of the swash plate either in the direction of maximum delivery rate or variable delivery rate.

Automatic air conditioning OFF

When the automatic air conditioning is switched off with the A/C ON/OFF switch, the refrigerant compressor control valve is opened completely. This allows refrigerant to flow unimpeded from the high pressure side into the crankcase leading to an extremely rapid increase in the crankcase pressure. This causes the coil body for closing the refrigerant compressor to move to the right against the valve plate until the refrigerant flow is shut off completely on the suction side.

The coil body is designed such that at a delivery rate of 5 cm, the refrigerant flow is interrupted by closing off the intake passage, even when the refrigerant compressor is active.

Internal refrigerant compressor lubrication when air conditioning switched off

The refrigerant compressor has an internal lubricant circuit to ensure lubrication of the mechanical moving parts such as the sliding shoe, swash plate, front and rear radial shaft bearings, pistons and cylinder liner. Lubrication is ensured by way of a minimum refrigerant compressor delivery rate. This delivery rate is regulated by 2 valves. The minimum refrigerant compressor delivery rate of 2% when the refrigerant compressor is switched off ensures that the refrigerant with the compressor oil present in the crankcase is transported through the bored refrigerant compressor shaft.

The mixture of refrigerant and refrigeration oil enters the crankcase on the intake side where it is compressed and then pumped into the refrigerant circuit on the pressure side. From the pressure side, the mixture of refrigerant and refrigeration oil flows back through a valve into the crankcase.

The refrigerant compressor output is regulated depending on the air humidity

The regulation of the refrigerant compressor output depends on the air humidity measured by the dew point sensor (B11/12). The air around the evaporator is no longer cooled down to approx. 3°C, as previously, in order to then be heated back up to the desired temperature (Reheat mode). Reheat mode only takes place, if the reheat-associated air dehumidification effect is required to keep the windows condensation-free when humidity is high. Various regulations zones are differentiated depending on the relative air humidity.

Relative air humidity and operating condition

0 to 60% No reheat mode

40 to 90 Reheat mode with variable temperature control between 0 and 12°C

80 to 100% Full reheat mode

Outside air humidity

If the outside air is extremely moist, the refrigerant compressor operates at maximum capacity, i.e. the evaporator temperature is low (approx. 2°C), for maximum air dehumidification. In heating mode, post heating is accordingly performed using the heat exchanger.

Dry outside air

With dry outside air the refrigerant compressor operates with reduced power output, i.e. the evaporator temperature can be up to approx. 14°C, if no lower outlet air temperature becomes necessary.

The air humidity control is installed only on vehicles with comfort automatic air conditioning, code 581

Evaporator temperature sensor, component description - GF83.57-P-2126RT

MODEL 251.1/0 up to Model Year 8

Scheme 180

Location

The evaporator temperature sensor is located on the left side of the air conditioner housing.

Task

The evaporator temperature sensor measures the temperature of the air flowing past the evaporator. The reading is read in directly by the AAC control and operating unit (N22) or comfort AAC control and operating unit (N22/7).

Function

The evaporator temperature sensor is a temperature-dependent resistor. Controlled regulation of the refrigerant compressor (A9) using the values received from the AAC control and operating unit or comfort AAC control and operating unit, prevents the evaporator from icing up. The refrigerant compressor is switched off at an evaporator temperature of 2 degrees Celsius.

Evaporator temperature sensor, component description - GF83.57-P-2126RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on BR 251

Scheme 181

Location

The rear air conditioning evaporator temperature sensor is located at the top of the evaporator of the rear air conditioner.

Task

The rear air conditioning evaporator temperature sensor measures the temperature of the air flowing past the evaporator. The reading is read in directly by the comfort AAC [KLA] control and operating unit (N22/7).

Function

The evaporator temperature sensor is a temperature-dependent resistor. Controlled regulation of the refrigerant compressor (A9) based on the values received from the comfort AAC [KLA] control and operating unit prevents the evaporator from icing up.

In-car temperature sensor, component description - GF83.57-P-2127RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Scheme 182

Location

The air conditioning temperature sensors are installed in the individual air outlet ducts, as shown in the figure.

Scheme 183

Location

The center outlet temperature sensors are installed as shown in the figure.

Task

The temperature sensors measure the temperature of the air flowing out of the specific air flap and transfer this value to the AAC control and operating unit (N22).

The temperature reading for the exiting air is compared with the settings on the temperature selector wheel by the AAC control and operating unit. The blending air flap is readjusted, depending on the result. In addition, this also measures the recirculated interior temperature.

In-car temperature sensor, component description - GF83.57-P-2127RTK

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Scheme 184

Scheme 185

Scheme 186

Scheme 187

Task

The temperature sensors measure the temperature of the discharged air at the particular air flap and forward them to the comfort AAC [KLA] control and operating unit (N22/7).

The comfort AAC control and operating unit compares the measured temperature value of the discharged air to the setting on the temperature selector wheel. The blending air flap is readjusted, depending on the result. In addition, this also measures the recirculated interior temperature.

Sun sensor, component description - GF83.57-P-2128RT

MODEL 251.1/0 with CODE (580) Automatic air conditioning up to Model Year 8

Exemplified on model series 164

Scheme 188

Location

The sun sensor is located behind the instrument cluster (A1) in the instrument panel.

Task

The sun sensor measures the intensity of the sun radiation acting on the vehicle. The interior temperature and blower speed are adapted according to the intensity.

The reading is read in directly by the AAC control and operating unit (N22).

Among other items, evaluation of the sun sensor depends on whether an infrared insulating windshield is installed. In this case, the values read in are evaluated at a rate of only 66% for control.

Dual sun sensor, component description - GF83.57-P-2129RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning up to Model Year 8

Exemplified on model series 164

Scheme 189

Location

The dual sun sensor is located on the dashboard behind the center nozzles.

Task

The dual sun sensor is only processed by the comfort AAC [KLA] control and operating unit (N22/7). The dual sun sensor is capable of measuring the intensity of the radiation (brightness) of the solar radiation with the aid of a photodiode.

The dual sun sensor differentiates between left and right solar incidence, in other words it has two photodiodes. The interior temperature and the blower stage are adjusted based on the intensity of the light.

Among other items, evaluation of the sun sensor depends on whether an infrared insulating windshield is installed. In this case, the values read in are evaluated at a rate of only 66% for control.

Outside air temperature sensor, component description - GF83.57-P-4000RT

MODEL 251.1/0 up to Model Year 8

Scheme 190

Location

The Outside temperature indicator temperature sensor is located in the front left bumper.

Task

To record the outside temperature.

Function

The outside temperature indicator temperature sensor is an NTC resistance. This changes its resistance depending on the outside temperature. It is read in by the AAC [KLA] control and operating unit (N22).

Outside temperature display temperature sensor, component description - GF83.57-P-4002RT

MODEL 251.1/0 up to Model Year 8

Scheme 191

Location

The temperature sensor is located on the left front bumper.

Task

To record the outside temperature.

Function

The temperature sensor changes its resistance depending on the outdoor temperature. It is read in by the instrument cluster (A1) and the reading is indicated on the multifunction display (A1p13).

Scheme 192

Scheme 193

Scheme 194

Scheme 195

Table of contents: Function description of stationary heater (STH) - GF83.70-P-0996GM

MODEL 164.1 as of model year 09/YoM 08 model refinement package with CODE (228) Stationary heater

MODEL 164.8,251.0/1 as of model year 09/YoM 08 with CODE (228) Stationary heater

Table of contents: Function description of stationary heater (STH) - GF83.70-P-0996GZ

MODEL 164,251 up to Model Year 8 Nur ECE-Fahrzeuge

STH control unit, component description - GF83.70-P-4200GM

MODEL 164.1 as of model year 09/YoM 08 model refinement package with CODE (228) Stationary heater

MODEL 164.8, 251.0/1 as of model year 09/YoM 08 with CODE (228) Stationary heater

Shown on model 164.1

Scheme 196

Location

The STH control unit is integrated in the STH heater unit (A6), which is located in the left front fender behind the front wheel.

Illustrated on model 251

Scheme 197

Location

The STH control unit is integrated in the STH heater unit, which is located in the right fender at the top behind the front wheel.

Task

The STH control unit has the following tasks

1. Reading in of signals
2. Evaluation of input factors
3. Actuation of components

Reading in of signals

The input factors are read in with the following connections

1. Direct line
2. Interior CAN

Direct line

The following signals are read in via a direct line

1. STH radio remote control receiver (A6/1)
2. Temperature sensor (A6b1)
3. Thermal fuse (A6f1)
4. Glow pin unit flame monitor (A6r4)

If the temperature of T = 125°C is exceeded in the STH heater unit, the thermal fuse detects overheating and triggers the heater unit fault run-on process for approx. t = 120 s followed by fault interlock

Interior CAN

The following signals are read in with interior CAN by the: by the EZS control unit (N73)

1. Circuit status

From the upper control panel control unit (N72/1)

1. Status of STH switch (N72/1s30) by the instrument cluster (A1)
2. Preselection time

By the AAC [KLA] control and operating unit (N22) (without code (581) Comfort automatic air conditioning) or at the comfort AAC [KLA] control and operating unit (N22/7) (with code (581) Comfort automatic air conditioning)

1. Ventilation or heating
2. Ambient temperature

Evaluation of input factors

The input factors that have been read in are evaluated by the integrated microprocessor and the relevant components are then actuated.

Actuation of components

Components are actuated with the following lines

1. Direct line
2. Interior CAN

Direct line

1. Glow pin unit flame monitor
2. Fuel preheating system (A6r5) (with diesel engine)
3. Auxiliary heater metering pump (M46/1)
4. STH switchover valve (Y16)

Interior CAN

The following components are actuated with the interior CAN: By the upper control panel control unit

1. STH switch

The following components are actuated via a direct line

1. STH radio remote control receiver
2. Circulation pump (A6m1)
3. Combustion air blower (A6m2)

Variants

1. Gasoline version
2. Diesel version

STH control unit, component description - GF83.70-P-4200RT

MODEL 251 up to Model Year 8 Nur ECE-Fahrzeuge

Scheme 198

Location

The STH control unit is integrated in the STH heater unit (A6), which is located in the fender in the top right behind the front wheel.

Task

The STH control unit ensures that the vehicle interior is heated or ventilated to the target temperature set at the AAC [KLA] control and operating unit (N22).

The AAC [KLA] control and operating unit decides, depending on the outside or inside temperature, whether heating or ventilation is required

Cooling down to below the outside temperature is not possible during ventilation.

Reading in of sensors integrated in the STH heater unit

1. Glow pin unit flame monitor (A6r4)
2. Temperature sensor (A6b1)
3. Thermal fuse (A6f1)

Control and power supply of internal components

1. Combustion air blower (A6m2)
2. Glow pin unit flame monitor
3. Fuel preheating system (A6r5) (diesel only)

Control and power supply of external components

1. STH switchover valve (Y16)
2. Auxiliary heater metering pump (M46/1)

Control of external components

1. Blower motor (A32m1)

Safety shutoff if an accident occurs

The restraint systems control unit (N2/7) transmits the crash signal via CAN-C to the central gateway control unit (N93), which places the signal on CAN-B. The front SAM control unit (N10) receives the crash signal and switches the stationary heater permanently off. The safety shutoff can only be reset via diagnosis.

Shutoff via thermal fuse

In the event of a temperature control error or due to overheating, e.g. as a result of a lack of water, the thermal fuse switches the STH heater unit permanently off when 125°C are exceeded.

Operation after shutoff via the thermal fuse resumes

1. via diagnosis or
2. by breaking the contact of the power supply for a short period of time (e.g. removing the fuse). To do this, the STH switch (N72/1s30) must first be operated for at least 5 s up to a maximum of 15 s. After releasing the STH switch, the fuse must be removed within 30 s to achieve a reset of the thermal fuse.

Discrete inputs

1. Circuit 30
2. Circuit 31
3. STH radio remote control receiver (A6/1)

Discrete outputs

1. Auxiliary heater metering pump
2. STH switchover valve

Operating time for heater and ventilation

In the basic setting, the maximum heating time is 50 min. It is possible to change it via diagnosis in 10 min increments between 10 and 60 min.

The maximum ventilation time is limited to a maximum of 50 min in the basic setting, as is the heating time, unless a shortening factor was set via diagnosis.

The following shortening factors can be set

1. Factor 1: ventilation time = 1/3 heating time
2. Factor 2: ventilation time = 1/2 heating time
3. Factor 3: ventilation time = 1/4 heating time

STH radio remote control receiver component description - GF83.70-P-4201RT

MODEL 251 up to Model Year 8

Nur ECE-Fahrzeuge

Scheme 199

Location

The STH radio remote control receiver is installed in the left footwell in front of the 2nd seat row.

Task

The STH radio remote control receiver evaluates the signals of the transmitter key (A8/1) and forwards them to the STH control unit (A6n1).

When a valid signal is received, a return signal is sent to the transmitter key.

Before initial startup, the STH radio remote control receiver must teach in the transmitter keys (a maximum of 3 each) allocated to it

STH heater unit component description - GF83.70-P-4202RT

MODEL 251 up to Model Year 8

Nur ECE-Fahrzeuge

Scheme 200

Location

The STH heater unit is located in the fender in the top right behind the front wheel.

Task

Heating the vehicle interior to the target temperature set in the AAC [KLA] control and operating unit (N22).

Design

The components required for generation and transfer of heat are integrated into the STH heater unit

1. Temperature sensor (A6b1)
2. Thermal fuse (A6f1)
3. Combustion air blower (A6m2)
4. STH control unit (A6n1)
5. Glow pin unit flame monitor (A6r4)
6. Fuel preheating system (A6r5) (diesel only)

Function

The start, regulation and ending of heater operation is controlled by the integrated STH control unit.

STH fuel metering pump component description - GF83.70-P-4203GZ

MODEL 164,251 up to Model Year 8

Nur ECE-Fahrzeuge

Illustrated on model 251

Scheme 201

Location

The auxiliary heater metering pump is located at the right vehicle floor, in front of the fuel tank.

Task

The auxiliary heater metering pump is a combined supply, metering, and shutoff system. Actuated by the STH control unit (A6n1), it supplies the fuel required for combustion from the vehicle's fuel tank to the STH heater unit (A6) and shuts off the feed line when the STH heater unit has stopped.

STH radio remote control transmitter, component description - GF83.70-P-4204GZ

MODEL 164, 251 up to 31.5.07

ECE vehicles only

Scheme 202

Task

The STH transmitter enables heater or ventilation operation on the stationary heater (STH) to be started and ended at the press of a button (1, 2).

The stationary heater transmitter has a max. range of approx. 300 m, which can be reduced depending on the environment (e.g. buildings).

The indicator lamp in the stationary heater transmitter may display the following

1. Indicator lamp (green or red) is continuously on for 2 s: Correct wireless connection to the vehicle has been established.
2. Indicator lamp (green or red) flashes for 2 s: Correct wireless connection to the vehicle has not been established.
3. Indicator lamp (orange) is continuously on for 2 s before the green or red signal (regardless whether it flashes or is continuously on): The battery in the transmitter key is weak but transmission is still possible.
4. Indicator lamp (orange) flashes for 5 s: The battery in the transmitter key is too weak for transmission.

Before initial startup the STH radio remote control receiver (A6/1) must teach in the STH transmitters allocated to it

STH radio remote control transmitter, component description - GF83.70-P-4204RT

MODEL 164, 251 as of 1.6.07 up to Model Year 8

Nur ECE-Fahrzeuge

Scheme 203

Design

The stationary heater transmitter consists essentially of a radio transmitter, two-way radio receiver and the following display and control elements

1. Display (1)
2. Right arrow button (2)
3. Left arrow button (5)
4. ON button (4)
5. OFF button (3)

Task

The stationary heater transmitter can be used to

1. switch the stationary heater (STH) on and off
2. call up the stationary heater's operating condition

The roof antenna module (A2/93) receives the radio signal and forwards it via the telephone/cell phone/STH radio remote control antenna splitter (A2/53) to the receiver of the stationary heater radio remote control (A6/1). From there the request is forwarded to the stationary heater control unit (A6n1).

The stationary heater transmitter has a max. range of approx. 300 m (depending on the environment)

Operating condition query

A single actuation of one of the arrow buttons on the stationary heater transmitter can at any time call up an inquiry of the operating condition, irrespective of the manner in which the stationary heater was activated. The corresponding stationary heater status is shown on the display.

STH switchover valve component description - GF83.70-P-4205RT

MODEL 251 up to Model Year 8

Nur ECE-Fahrzeuge

Scheme 204

Location

The STH switchover valve is located in the engine compartment behind the right front lamp unit (E2).

Task

Actuated by the STH control unit (A6n1), the STH switchover valve regulates the coolant flow between the heater heat exchanger (small coolant circuit) and the engine (large coolant circuit).

This enables the interior compartment to be heated up faster.

Overview of system components for stationary heater (STH) - GF83.70-P-9996GM

MODEL 164.1 as of model year 09/YoM 08 model refinement package with CODE (228) Stationary heater

MODEL 164.8,251.0/1 as of model Year 09/YoM 08 with CODE (228) Stationary heater

Overview of system components for stationary heater (STH) - GF83.70-P-9996GZ

MODEL 164, 251 up to Model Year 8

Nur ECE-Fahrzeuge

Coolant circulation pump, component description - GF83.75-P-2110RT

MODEL 251.1/0 up to Model Year 8

Scheme 205

Location

The coolant circulation pump is located in the front right section of the engine compartment.

Task

The coolant circulation pump serves

1. for support when the engine is running or, with residual heat mode or stationary heater switched on (stationary heater, code 228), for pumping the coolant through the heater heat exchanger.

Function

The coolant circulation pump is controlled directly by the AAC control and operating unit (N22) or comfort AAC control and operating unit (N22/7).

Additional circulation pump, component description - GF83.75-P-2111RT

MODEL 251.1/0 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

MODEL 164.8 with CODE (581) Comfort automatic air conditioning with CODE (582) Rear air conditioner up to Model Year 8

Shown on BR 251

Scheme 206

Location

The rear AC additional circulation pump is located at the right front in the engine compartment.

Task

The rear AC additional circulation pump is installed to support the coolant circulation pump (M13). The circulation pumps cool the engine after the ignition has been switched off and transport the heating water in residual heat mode.

Function

The additional circulation pump and the coolant circulation pump are directly actuated by the comfort AAC [KLA] control and operating unit (N22/7).