Mercedes-Benz ML320. Service manual - part 688

TEMPERATURE CONTROL, FUNCTION - GF83.57-P-2000GI

MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning

Function

The electronically controlled cooling, heating and ventilation system of the automatic air conditioning achieves
the desired in-car temperature as rapidly as possible or maintains it constantly.

The following options are available for this purpose:



the evaporator cooling the air



the heating system heat exchanger heating the air

Temperature control

The temperature values needed for the temperature control are determined by the in-car temperature sensors
(N22b1), center nozzle air stream (B10/24), footwell at front (B10/25), rear (B10/7), outside temperature
indicator (B14) and defroster protection (R35).

The electronics of the AAC push-button control module (N22) compare the various test values with the
temperature preselected at the temperature selector wheel.

As required, the automatic air conditioning performs the regulation in that in heating mode it controls the
position of the blending air flaps, via the blending air flap actuator motor (M2/6), or in cooling mode it actuates
the refrigerant compressor and thus keeps the respective setting constant.

CDI control module, location/task/function

Engine 612.963

GF07.16-P-
3102IA

Temperature selector wheel, location/task/ design/function

GF83.25-P-
2102GI

Heating system heat exchanger, location/ purpose/function

GF83.20-P-
2108GC

Evaporator, location/purpose/design/function

GF83.40-P-
2121GC

Expansion valve, location/task/design/function

GF83.40-P-
2123GC

Refrigerant compressor, location/task/design/ function

GF83.55-P-2100P

Control valve, location/task/function

GF83.55-P-2102P

In-car temperature sensor, location/task/function

GF83.57-P-
2115GI

Center nozzle air stream temperature sensor,
location/task/function

GF83.57-P-
2116GI

Front footwell air stream temperature sensor,

GF83.57-P-

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

IN-CAR TEMPERATURE SENSOR WITH ASPIRATOR BLOWER, LOCATION - GF83.57-P-2100-01GH

The in-car temperature sensor (B10/4) is located on the center console on the left next to the radio. The aspirator
blower (M9) associated with the in-car temperature sensor is located at the bottom left on the evaporator
housing.

Fig. 118: Identifying In-Car Temperature Sensor

IN-CAR TEMPERATURE SENSOR WITH ASPIRATOR BLOWER FUNCTION - GF83.57-P-2100-02GH

Function

location/task/function

2117GI

Rear air stream temperature sensor, location/ task/function

GF83.57-P-
2118GI

Defroster protection temperature sensor, location/task/function

GF83.57-P-
2113GH

Blending air flap actuator, location / task / function

GF83.57-P-
2112GI

Outside temperature indicator temperature sensor,
location/task/function

GF83.57-P-
2119GI

Sun sensor position/task/function

GF83.57-P-
2111GI

Electric heater booster position/task/design/ function

Engine

612.963

GF83.70-P-
4054GH

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

The in-car temperature sensor (B10/4) is equipped with an aspirator blower which constantly draws air out of
the vehicle interior for the temperature measurement when the ignition is ON . The in-car temperature sensor
(B10/4) records the interior temperature and conveys it to the AAC push-button control module. A comparison
is made there with the setting on the temperature selector and the blend air flap is repositioned depending on the
result of this comparison.

It is connected to the AAC push-button control module via a separate electric cable.

Constant circulation of the interior air at the in-car temperature sensor (B10/4) is achieved by the in-car
temperature sensor aspirator blower (M9) and therefore ensures a high level of control accuracy.

In contrast to the previous suction jet nozzle a high level of control accuracy is ensured by the in-car

temperature sensor aspirator blower (M9).

OUTSIDE AIR TEMPERATURE SENSOR FUNCTION - GF83.57-P-2103-01GH

Function

The resistance of the outside air temperature sensor (B10/5) depends on the ambient temperature and the ground
speed. With an increase in the outside temperature, its resistance decreases. This information is sent to the air
conditioning control module (N19). This information causes a slight lowering or raising of the temperature
selected at the air conditioning control panel.

This achieves an adaptation to the temperature perception of the occupants.

The outside temperature depends on the ground speed, which prevents a value for the outside temperature that is
too high - as may occur when the vehicle is stationary or when traveling slowly, e.g. due to thermal radiation
from the engine - from being sent to the air conditioning control module (N19).

The value of the ground speed is sent from the traction systems control module (N47) via the instrument cluster
(A1) to the air conditioning control module (N19).

When switching the ignition off and on and with speeds lower than 20 km/h the temperature measured last is
used.

OUTSIDE AIR TEMPERATURE SENSOR POSITION - GF83.57-P-2103-02GH

The outside air temperature sensor (B10/5) is located at the front on the air inlet of the evaporator housing.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

Fig. 119: Identifying Outside Air Temperature Sensor

BLENDING AIR ACTUATOR, LOCATION - GF83.57-P-2105-01GH

The blending air flap actuator motor (M16/8) is located at the top in the center on the evaporator housing.

Fig. 120: Identifying Blending Air Flap Actuator Motor

BLENDING AIR FLAP MOTOR FUNCTION - GF83.57-P-2105-02GH

Function

The blending air flap actuator motor (M16/8) is actuated via the air conditioning control module depending on
the position of the temperature selector wheel in the air conditioning control panel and the actual in-car
temperature.

2001 Mercedes-Benz ML320

1998-2005 HVAC Climate Control - 163 Chassis

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