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Fig. 75: Identifying Automatic Air Conditioning Box Function - Operating Condition Air Ducting In
Blending Mode (Hot/Cold) Closed-Loop Operation
Operating condition: Blend air (warm/cold) Function
When in blending mode, the blower motor (5) draws in fresh air (A) to the automatic air conditioning box and
routes it through the multipurpose filter (3). The air cleaned by the multipurpose filter (3) is then routed to the
evaporator core (2) and dried there. Some of the dried, cooled and filtered air (B) is routed onwards by the heat
exchanger (1) and some is routed around the heat exchanger (1). This air conduction is controlled via the center
setting of the blending air flaps (6).
The dried, cooled and filtered air (B) which was routed through the heat exchanger (1) is then heated up again.
After passing through the blending air flaps (6) this heated air (C) is mixed up to form blend air (D) with the
dried, cooled and filtered air, which was routed around the heat exchanger (1). This blend air (D) is then routed
via the air outlets (E, F, FR, M and S) into the passenger compartment. The fresh air/recirculated air flap (4) is
closed.
Operating condition: Air ducting "recirculation air" in cooling mode
2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 76: Identifying Automatic Air Conditioning Box Function - Operating Condition Air Ducting
Recirculation Air In Cooling Mode
Operating condition: Cooling down "recirculation air" Function
In cooling mode with recirculated air, the blower motor (5) draws in recirculated air (A) from the passenger
compartment via the opened fresh air/recirculated air flap (4) into the automatic air-conditioning box and routes
it through the multipurpose filter (3). The air cleaned by the multipurpose filter (3) is then routed to the
evaporator core (2) and dried there. The dried, cooled and filtered air (B) is then routed around the heat
exchanger (1). This air conduction is controlled via the setting of the blend air flap (6).
The dried, cooled and filtered air (B) is routed directly into the passenger compartment via the air outlets (E, F,
FR, M and S). The supply of fresh-air is cut off by the fresh air/recirculation flap (4).
AUTOMATIC AIR CONDITIONING BOX, DESIGN - GF83.40-P-2105-04GI
The automatic air conditioning box consists of the following components
Air ducting flaps
Combination filter
Blower motor
Blower regulator
Evaporator
Heating system heat exchanger
Expansion valve
2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Blending air flap actuator
Fresh air/recirculated air flap actuator
Defroster vent flap actuator motor
Rear shutoff flap actuator motor
Footwell flap actuator
Electric heater booster (for engine 612.963 only) and therefore forms a complete unit.
AIR CONDITIONER HOUSING, LOCATION / TASK / DESIGN / FUNCTION - GF83.40-P-2105GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Fig. 77: Identifying Automatic Air Conditioning Box
Automatic air
conditioning box,
locationThe Automatic air conditioning box (1) is below the instrument
panel.
Automatic air
conditioning box,
purposeThe 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.
Automatic air
conditioning box,
design
GF83.40-P-
2105-04GI
Automatic air
conditioning box with engine 112, 113GF83.40-P-
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1998-2005 HVAC Climate Control - 163 Chassis
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Page 3340 of 4133

AC OFF BUTTON, FUNCTION - GF83.40-P-2107-01GI
Function
When the AC OFF button ( ) on the automatic air conditioning push-button control module is pressed an
LED comes on, the refrigerant compressor is switched off and cooling therefore switched off The air is no
longer cooled and dried.
Vehicles with diesel engine:
Additionally the electric heater booster is switched off. All other functions are retained.
In order to switch off the refrigerant compressor the push-button control module sends a switch-off request over
the CAN. At the same time, the compressor torque value is set to "0". After a specified time delay the
refrigerant compressor is switched off.
AC OFF BUTTON, LOCATION/TASK/FUNCTION - GF83.40-P-2107GI
MODEL 163 as of 1.9.01 with CODE (580a) Automatic air conditioning
Fig. 78: Identifying Temperature Thumbwheel And AC OFF Button
function2105-02GI
Maximum heating mode for vehicles equipped with engine
612.963 onlyGF83.40-P-
2105-02GJ
AC OFF
button,
locationThe AC OFF button ( ) is located at the center of the lower half of
the temperature selector wheel (2) on the AAC push-button control
module (N22).
AC OFF
button, taskThe AC OFF button ( ) serves to switch the automatic air
conditioning on and off. Function feedback is by way of a red LED.
AC OFF
button,
function
GF83.40-P-
2107-01GI
2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Page 3341 of 4133

REST BUTTON, FUNCTION - GF83.40-P-2109-01GI
Function
Pressing the reset button ( ) on the AAC push-button control module (N22) switches on the residual engine
heat utilization system. When the engine is switched off, the residual heat heats the vehicle depending on the
temperature setting on the AAC push-button control panel (N22) and the ambient temperature in the vehicle
interior. The vehicle can be heated for approx. 30 min, with the engine switched off. The function is only
available with the ignition switched off or in position 1. If there is low voltage, the residual heat function is
automatically switched off.
The flaps are in automatic mode and the quantity of air is also automatically regulated.
The residual heat function is switched off,
if the electronic key is moved to position 2 in the starter switch,
after approx. 30 minutes,
if the battery voltage drops below 11V.
AUXILIARY FAN, FUNCTION - GF83.40-P-2115-01GH
Function
Depending on the refrigerant pressure and/or the coolant temperature the left auxiliary fan (M4m1), right
auxiliary fan (M4m2) are actuated.
The all-activity module (AAM) (N10) receives the coolant temperature from the coolant temperature sensor and
the refrigerant pressure from the refrigerant pressure sensor (B12).
The all-activity module (AAM) (N10) compares this input information with stored values and actuates the left
auxiliary fan (M4m1), right auxiliary fan (M4m2).
When the following values are indicated the left auxiliary fan (M4m1), right auxiliary fan (M4m2) are switched
on or off:
refrigerant pressure >16 bar = auxiliary fan ON
refrigerant pressure < 12 bar = auxiliary fan OFF
coolant temperature > 105°C = auxiliary fan ON
coolant temperature < 94°C = auxiliary fan OFF
AUXILIARY FAN, FUNCTION - GF83.40-P-2115-01GI
Function
Depending on the refrigerant pressure and/or the coolant temperature the left auxiliary fan (M4m1) and the right
auxiliary fan (M4m2) are actuated.
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1998-2005 HVAC Climate Control - 163 Chassis
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The all-activity module (AAM) (N10) receives the coolant temperature by the coolant temperature sensor
(B11/4) and the refrigerant pressure by the refrigerant pressure and temperature sensor (B12/2). The all-activity
module (AAM) (N10) compares this input information with stored values and actuates the left auxiliary fan
(M4m1) and the right auxiliary fan (M4m2).
When the following values are indicated the left auxiliary fan (M4m1), right auxiliary fan (M4m2) are switched
on or off:
refrigerant pressure >16 bar = auxiliary fan ON
refrigerant pressure <13 bar = auxiliary fan OFF
coolant temperature > 105°C = auxiliary fan ON
coolant temperature < 97°C = auxiliary fan OFF
AUXILIARY FAN, LOCATION - GF83.40-P-2115-02GH
The auxiliary fans are located (M4) directly in front of the condenser.
Fig. 79: Identifying Left Auxiliary Fan And Right Additional Fan
ENGINE/AIR CONDITIONING ELECTRIC FAN, FUNCTION - GF83.40-P-2118-01GH
Function
Depending on the refrigerant pressure and/or the coolant temperature the fan speed is increased infinitely.
Engines 612.963 and 628.963
The CDI control module (N3/9) receives the coolant temperature from the coolant temperature sensor and via
the all-activity module (AAM) (N10) via the CAN bus the refrigerant pressure from the refrigerant pressure
sensor (B12).
2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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This input information is relayed by the CDI control module (N3/9) to the integrated control module of the
electric engine/AC intake fan with integrated control (M4/7).
Engines 113.942 and 113.981
The all-activity module (AAM) (N10) receives the coolant temperature via the coolant temperature sensor and
the refrigerant pressure via the refrigerant pressure sensor (B12).
This input information is relayed by the all-activity module (AAM) (N10) to the integrated control module of
the engine and AC electric suction fan with integrated control (M4/7)
There the input information is compared with the stored values and, if necessary, the speed of the engine and
AC electric suction fan with integrated control (M4/7) is increased to 100 %.
The engine and AC electric suction fan with integrated control (M4/7) operates with AC switched on and in the
reheat mode for basic ventilation with a capacity of up to 20 %.
The basic ventilation can be switched off under the following conditions:
At an outdoor temperature of < or = 15°C the value of the outdoor temperature is transmitted from the
outside temperature sensor (B10/5) to the AC control module (N19).
The pressure-dependent fan speed remains the same.
At a vehicle speed of > 75 km/h
The vehicle speed value comes from the traction system control module via the instrument cluster (A1)
and CDI control module (N3/9), to the control module integrated in the electric suction fan engine and
AC with integrated control (M4/7). The pressure-dependent fan speed remains the same.
An overrun time of 60 s can be set in order to ensure that the engine and AC electric suction fan with integrated
control (M4/7) will continue to operate even where the refrigerant compressor is temporarily switched off by
the icing protection.
The engine and AC electric suction fan with integrated control (M4/7) has a power rating of 550W.
ELECTRIC FAN, ENGINE/AIR CONDITIONING, LOCATION - GF83.40-P-2118-02GH
The engine and AC electric suction fan with integrated control (M4/7) is located immediately in front of the
condenser.
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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 80: Identifying AC Electric Suction Fan With Integrated Control
CONDENSER FUNCTION - GF83.40-P-2120-01GC
Function
The hot, gaseous refrigerant routed into the condenser passes the heat (compression heat) to the coiled pipes and
slats. These then very quickly absorb the refrigerant's heat and transmit the heat to the outside air passing
through. This in turn cools the refrigerant.
By cooling down, the refrigerant is liquefied (condensed). The liquid heat refrigerant is then carried away from
the condenser and flows into the fluid reservoir.
CONDENSER, LOCATION - GF83.40-P-2120-02GH
The condenser (7) is located directly in front of the radiator.
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1998-2005 HVAC Climate Control - 163 Chassis
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