1997 MERCEDES-BENZ ML350 sensor

The residual engine heat utilization system allows the vehicle to be heated even when the ignition is
switched OFF. To do so the system utilizes the residual heat from the engine and guides it via the
blower into the passenger compartment. The heating water circulation pump ensures that the
coolant is properly circulated.
Automatic air conditioning push-button control module
The automatic air conditioning can be operated by the driver using various tip switches. Apart from this
the push-
button control module reads in different sensor signals, processes them and controls components
in the automatic air conditioning.
Rear ventilation control panel
The operator can intervene in the automatic regulation of the rear ventilation through the automatic air
conditioning by using the rear ventilation control panel and adjust it accordingly to suit needs at any
given time. With the aid of the air distribution switch and blower switch the operator can accommodate
his/her own wishes. The correspondingly altered function is then no longer regulated by the automatic air
conditioning.
By pressing the automatic control button the manually initiated settings can be reset and thus regulated
again by the automatic air conditioning.
Regulation of the air quantity and air distribution ensues thus solely by way of the automatic air
conditioning push-button control module.
Heater circuit
Coolant is heated by the engine. Subsequently, the heated coolant is then routed through the heat exchanger,
where the heat is dissipated to the air in the passenger compartment. The heater return line, in which the heating
water circulation pump is located, takes the coolant back to the coolant pump.
The heating water circulation pump ensures that the coolant is properly circulated.
The coolant flows through the heat exchanger permanently.
Depending upon the desired in-car temperature, regulation is conducted over the blending air flaps, which are
operated by the blending air flap actuator motor.
Heater operation with heater booster in vehicles with OM 612.963
In vehicles equipped with direct-injection diesel engines, an electrical heater booster is additionally installed in
the evaporator housing downstream of the heat exchanger, in order to compensate the heater output deficit
which occurs in the case of certain operating conditions.
The 3 heating elements in the heater booster are supplied with current, as a result of which they are heated and
start to glow. As a result of the structural conditions, it is ensured that the drawn in fresh air flows directly past
the electric heater booster, and is therefore heated.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 81 © 2006 Mitchell Repair Information Company, LLC.

AUTOMATIC AIR CONDITIONING PUSH-BUTTON CONTROL MODULE, FUNCTION - GF83.40-P-2000GI
MODEL 163 as of 1.9.01 with CODE (580a) Automatic air conditioning
Fig. 69: Identifying Blower Switch , Temperature Selector Wheel, Air Di stribution Switch And Interior
Air Temperature Sensor
Function
The AAC push-button control module (N 22) makes it possible to make adjustments coming from the driver
such as:
air quantity, by adjusting the blower switch setting (1)
temperature by setting the temp erature selector wheel (2)
air distribution, by setting the air distribution switch (3)
defrost function by pressing the defroster button ( )
recirculated air mode by pressing th e recirculated air push-button ( )
automatic air distribution/blower speed by pressing the Auto
switching off the cooling by pressing the AC button ( )
activating the residual engine heat ut ilization system with the ignition switched of f by pressing the REST
button ( )
heating the rear window by pressing the rear window heating button ( )
switching off the air distribution to the rear compartment by pressing the rear compartment air
distribution button ( )
612.9632005GH
Residual engine heat util ization system, function GF83.75-P-
2000GI
Automatic air conditioning sy stem component summary,
location/purpose/design/function GF83.40-P-
9990GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 83 © 2006 Mitchell Repair Information Company, LLC.

The control module integrated in the AAC push-button control module (N22) looks after all system regulation
and control functions such as:
comparing preselected and actual temperatures and controlling the air temperature at the air outlets
automatic switchover from fresh air to recirculated air mode
electrical control of refrigerant compressor
controlling the auxiliary fan or the electric suction-type fan motor/ air conditioning with integrated
control
The AAC push-button control module (N22) has a diagnostic capability. Consequently, any faults which occur
are stored in the fault memory which can be read with the help of the diagnosis assistant system (DAS).
When the AAC push-button control module is replaced (N22), variant coding must be carried out using the
Diagnosis Assistant System (DAS).
The AAC push-button control module (N22) also performs the following actuations:
direct: refrigerant compressor; heating water circulation pump; PTC heater booster (OM 612 only), rear
window heater
via the CAN BUS: auxiliary fan, electric suction-type fan motor/air conditioning with integrated control,
blower control and air distribution in the rear compartment (automatic mode)
via the AC bus: blower motor; 8 stepping motors for air distribution
The following sensor signals are read in by the AAC push-button control module (N22):
direct: temperature sensor evaporator, pressure and temperature sensor refrigerant, in-car temperature
sensor, center nozzle vent air temperature sensor, footwell and rear passenger compartment, sun sensor
via the CAN BUS: Ambient temperature display temperature sensor, sensor for specified values in rear
control panel
REFRIGERANT CIRCUIT FUNCTION - GF83.40-P-2001GH
MODEL 163 up to 31.8.01 with CODE (580) Air conditioning or Tempmatic for USA
Blower switch, location/task/design/function GF83.25-P-2100GI
Temperature selector wheel, location/task/ design/function GF83.25-P-2102GI
Air distribution switch, location/task/design/ function GF83.25-P-2101GI
Defroster button, location/task/function GF83.40-P-2139GI
Recirculating air push-button, location/task/ function GF83.40-P-2145GI
Auto button, location/task/function GF83.40-P-2147GI
AC OFF button, location/task/function GF83.40-P-2107GI
Rest push-button, location/task/function GF83.40-P-2148GI
Rear passenger compartment air distribution button, location/task/function GF83.40-P-2173GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 84 © 2006 Mitchell Repair Information Company, LLC.

REFRIGERANT CIRCUIT, FUNCTION - GF83.40-P-2001GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Auxiliary fan, location/task/function Engines 111.977, 112.942GF83.40-P-
2162GH
Electric fan motor/air conditioning,
location/task/function Engines 113.942/981 and
612.963GF83.40-P-
2151GH
Condenser position/task/function GF83.40-P-
2152GC
Evaporator, location/purpose/design/function GF83.40-P-
2121GC
Fluid reservoir (TAC), location/task/function GF83.30-P-
2120GC
Expansion valve, location/task/design/function GF83.40-P-
2123GC
Refrigerant pressure sensor, location/task/ function GF83.40-P-
2156GH
Refrigerant compressor, location/task/design/
function GF83.55-P-
2100GH
Air conditioning control module, location/task/
function GF83.30-P-
2102GH
All-activity module, location/task/design/ function GF54.21-P-
4110GH
Extended-activity module, position/task GF54.21-P-
4106GH
Extended-activity module, location/task/designas of 1.12.99GF54.21-P-
4107GK
CDI control module, location/task/function Engine 612.963GF07.16-P-
3102IA

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 86 © 2006 Mitchell Repair Information Company, LLC.

REAR VENTILATION CO NTROL PANEL, FUNCTION - GF83.40-P-2007GI
MODEL 163 as of 1.9.01 with CODE (580a) Automatic air conditioning
N72/2s3 Rear ventilation control panel
Auto button
Air distribution button
Blower button
Auxiliary fan, location/purpose/function
with code 580 up to 31.08.01
Engine 112.942, 112.970 with
code 580a as of 01.09.01GF83.40-P-
2162GH
Engine and AC electric su ction fan with integrated
control, location/purpose/function
Engine 113.942 with code 580a up
to 31.08.01
Engine 113.981, 113.965, 612.963,
628.963 with code 580a as of
01.09.01
GF83.40-P-
2172GI
Condenser, location/purpose/function GF83.40-P-
2152GC
Evaporator location/purpose/design/function GF83.40-P-
2121GC
Fluid reservoir, location/purpose/function GF83.40-P-
2153GI
Expansion valve, locati on/purpose/design/ function GF83.40-P-
2123GC
Refrigerant pressure and temperature sensor,
location/purpose/function GF83.40-P-
2171GI
Refrigerant compressor, location/purpose/
design/function GF83.55-P-
2100P
Control valve, location/purpose/function GF83.55-P-
2102P
Belt pulley, location/ purpose/design/function GF83.55-P-
2103P
Pressure relief valve, location/purpose/function GF83.55-P-
2104P

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 88 © 2006 Mitchell Repair Information Company, LLC.

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.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 97 © 2006 Mitchell Repair Information Company, LLC.

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
me
Saturday, October 02, 2010 3:23:16 PMPage 98 © 2006 Mitchell Repair Information Company, LLC.

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.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:16 PMPage 99 © 2006 Mitchell Repair Information Company, LLC.