air condition MERCEDES-BENZ ML320 1997 Complete Repair Manual

and therefore forms a complete unit.
The heater housing distributes the air which is required to ventilate the vehicle interior to the relevant air ducts
and air outlets depending on the temperature desired in the interior.
The air ducting depends on various operating conditions such as:
Heating
No heating
Fresh air mode
Recirculated air mode
FRESH AIR/RECIRCULATED AIR FLAP, LOCATION - GF83.20-P-2104-01GH
The fresh air/recirculated air flap (1) is located at the top of the heater/A/C housing.
Fig. 40: Identifying Fresh Air/Recirculated Air Flap

FRESH AIR/RECIRCULATED AIR FLAP, FUNCTION - GF83.20-P-2104-02GH
Function
The fresh air/recirculated air flap is actuated by the fresh air/ recirculated air flap actuator (M2/5).
Fresh air mode

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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The fresh air/recirculated air flap shuts off the supply of recirculated air.
Fresh air is drawn in.
Recirculation mode
The fresh air/recirculated air flap shuts off the supply of fresh air. Air is drawn in from the passenger
compartment.
HEATER CORE, LOCATION/PURPOSE/FUNCTION - GF83.20-P-2108GC
MODEL 163, 168
HEATING WATER CIRCULATION PUMP, LOCATION/TASK/FUNCTION - GF83.20-P-2109GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Fig. 41: Identifying Heating Water Circulation Pump

Heater core,
locationModel 168GF83.20-P-
2101-02GC
Model 163GF83.20-P-
2101-02GH
Heater core,
purposeThe heater core serves for heating up the air flowing through on the way
to the various defroster, ventilation and heating nozzles in the vehicle
passenger compartment.

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

Heating water
circulation pump,
positionThe heating water circulation pump (M13) is located at the front
right in the engine compartment next to the coolant compensating
reservoir.


Heating water
circulation pump
taskThe heating water circulation pump (M13) serves to maintain a
constant flow of hot water through the heat exchanger in the event of
low engine speeds and residual engine heat utilization.


2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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HEATER HOUSING POSITION/TASK/FUNCTION - GF83.20-P-2110GC
MODEL 163 up to 31.8.01
168 up to except CODE (580) Air conditioning or Tempmatic for USA
Shown on model 168 as of 1.03.01
Fig. 42: Identifying Heater Housing
- Shown On Model 168 As Of 1.03.01
FRESH AIR/RECIRCULATED AIR FLAP, LOCATION/PURPOSE/FUNCTION - GF83.20-P-2111GC
MODEL 163, 168

Heating water
circulation pump
function
GF83.20-P-
2102-01GI
Heater housing
positionThe heater housing (1) is located beneath the instrument
panel.
Model 168 up to 28.02.01GF83.20-P-2103-
01GC
Model 163GF83.20-P-2103-
01GH
Heater housing task GF83.20-P-2103-
03GC
Heater housing
functionModel 168GF83.20-P-2103-
02GC
Model 163GF83.20-P-2103-
02GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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blower level 2 --> blower level 3
may lead to an increase in the speed of the blower motor due to the short-term bridging of two contact plates
(intermediate setting).
BLOWER SWITCH, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2100GC
MODEL 163 up to 31.8.01 168
Shown on model 168 with heating as of 01.03.01
Fig. 44: Identifying Blower Switch (Model 168 With Heating As Of 01.03.01)

BLOWER SWITCH, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2100GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Blower switch,
locationThe blower switch (N119s3) is located on the left in the heater
push-button control module.
Model 168 up to 28.02.01GF83.25-P-2100-
01GC
Model 163GF83.25-P-2100-
01GH
Blower switch,
taskThe blower switch activates several blower stages in fresh air
and recirculating air mode.
Blower switch
designThe blower switch is designed as a multi-level rotary switch with
an axis and wiper contact.
Blower switch,
function GF83.25-P-2100-
02GC

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 45: Identifying Blower Switch - Model 163 As Of 1.9.01 With Code (580a Automatic Air
Conditioning
AIR DISTRIBUTION SWITCH, FUNCTION - GF83.25-P-2101-01GH
Function
Turning the air distribution switch causes two wire cables to move the air distribution flaps, in order to route air
through the air distribution system to the air vents. The air vents are:
defroster vents for windshield/side windows
center air vents
lower air vents
There are 12 possible indented positions for air distribution.
AIR DISTRIBUTION SWITCH, FUNCTION - GF83.25-P-2101-01GI
Function
The air distribution can be set manually or automatically:
Manual
Turning the air distribution switch

Blower
switch,
location
The blower switch (1) is located on left in the AAC push-button control module (N22).
Blower
switch, taskThe blower switch (1) activates several blower stages in fresh air and recirculating air
mode.
Blower
switch designThe blower switch (1) is equipped with a rotary ring with which the blower levels can be
set. The LEDs in the rotary ring display the set blower level.

Blower
switch,
functionThe blower switch (1) sets the control voltage for the blower regulator in 6 stages and 5
intermediate settings via the push-button control module, depending on the setting. This
facilitates blower speed control of 0 -100 %.


2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 55 © 2006 Mitchell Repair Information Company, LLC.

Automatic
Pressing the Auto button ( )
Turning the air distribution switch on the AAC push-button control modul e (N22) actuates the various air
distribution actuators via air conditioner bus.
The following basic settings for air distribution are provided:
 Air flow from center and side vents
 Air flow at center, side,
footwell and defroster vents
 Air outlet at the center, side and defroster vents
 Air flow at center, side and footwell vents
Apart from the 4 listed basic settings, a furt her 8 intermediate settings can be selected.
AIR DISTRIBUTION SWITCH, LOCATION - GF83.25-P-2101-02GH
Heater depiction
The air distribution switch (3) is loca ted in the heater control unit (S98).
Fig. 46: Identifying Ai r Distribution Switch

AIR DISTRIBUTION SWITCH , LOCATION/TASK/DESIGN/F UNCTION - GF83.25-P-2101GH
MODEL 163 up to 31.8.01
Air distribution
switch, location GF83.25-P-
2101-02GH
Air distribution
switch, taskThe air distribution switch regulates the flow of air through the air
distribution system to the air vent s for ventilation of the passenger
compartment.


2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
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AIR DISTRIBUTION SWITCH, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2101GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Fig. 47: Identifying Air Distribution Switch
- Model 163 As Of 1.9.01 With Code (580a) Automatic Air
Conditioning
TEMPERATURE SELECTOR WHEEL, FUNCTION - GF83.25-P-2102-01GH
Function
Heating
By rotating the temperature selector wheel, a cable is moved via a disk cam, thereby actuating the blending air
flaps.
Air conditioning
The air temperature is regulated by a rotary control with a variable resistor. Signals from the resistor and AAC
control module determine the desired interior temperature. If the temperature selector wheel is turned in an anti-
Air distribution
switch, designThe air distribution switch is designed as a rotary switch with 12
indented positions for air distribution.
Air distribution
switch, function GF83.25-P-
2101-01GH
Air distribution
switch, locationThe air distribution switch (3) is located on the right in the AAC
push-button control module (N22).
Air distribution
switch, taskThe air distribution switch (3) controls the air flow to the air outlets
for ventilation of the passenger compartment.
Air distribution
switch, designThe air distribution switch (3) is equipped with a rotary ring, with
which the air distribution can be set. The LEDs in the rotary ring
display the air distribution level.

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

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 57 © 2006 Mitchell Repair Information Company, LLC.

TEMPERATURE SELECTOR WHEEL, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2102GI
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning
Fig. 49: Identifying Temperature Selector Wheel
- Model 163 As Of 1.9.01 With Code (580a) Automatic
Air Conditioning
AIR CONDITIONING (TAC) FUNCTION - GF83.30-P-0001GH
MODEL 163 up to 31.8.01 with CODE (580) Air conditioning or Tempmatic for USA
Function
The air conditioning's electronically controlled cooling, heating and ventilation system keeps the desired in-car
temperature constant. AC button ( ) pressed (illuminates).
wheel, tasktemperature desired in the vehicle interior.
Temperature selector
wheel design
Heater:
Rotary switch with disk cam, pivot, control-sleeve levers, as well
as micro stops and end stops Air conditioning Rotary switch with
potentiometer

Temperature selector
wheel, functionModel 168GF83.25-P-
2102-01GC
Model 163GF83.25-P-
2102-01GH
Temperature selector
wheel, locationThe temperature selector wheel (2) is located in the center in the
AAC push-button control module (N22).
Temperature selector
wheel, taskThe temperature selector wheel (2) serves to preselect the
temperature desired in the vehicle interior.
Temperature selector
wheel designThe temperature selector wheel (2) is equipped with a rotary ring,
with which the temperature values can be set. The LEDs in the
rotary ring display the set temperature level.

Temperature selector
wheel, function GF83.25-P-
2102-01GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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After starting, the refrigerant compressor starts up. If cooling is not necessary, the refrigerant compressor's
output is lowered and switched off via the icing inhibitor.
The air conditioning is always ready for operation after the engine has been started, and operates according to
the so-called "reheat" principle. This means: The refrigerant compressor always operates at an ambient
temperature in excess of 1°C, therefore also cools cold incoming air. Following the cooling process, the dried
air is heated at the heat exchanger.
On the one hand, this effect serves the purpose of comfort, because cooling also simultaneously causes air
dehumidification which, in turn, is an important prerequisite for a pleasant interior climate. On the other hand,
the air is dried as a result of this cooling and heating, thereby preventing window fogging.
Pressing the AC button again ( ) (does not illuminate) switches off the cooling.
Heating mode
The in-car temperature sensor measures the air temperature in the interior of the vehicle.
The air conditioning control module electronics compares the in-car temperature with the desired temperature
which has been set at the temperature selector wheels.
The microprocessor adjusts the air conditioning electronics or keeps the relevant setting constant as required.
Heater operation with heater booster in vehicles with engine 612.963 as of 12/99
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 any heater output deficit
which exists under certain operating conditions.
The 3 heating elements in the heater booster are supplied with current, whereupon they are heated and they 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.
Cooling mode
The icing inhibitor measures the temperature at the evaporator air outlet, while the interior temperature sensor
determines the relevant in-car temperature.
The air conditioning control module electronics compares the various measured values with the desired
temperature which has been set at the temperature selector wheels.
The microprocessor adjusts the air conditioning or keeps the relevant setting constant as required.
In-car temperature sensor replaced by new typeas of 1.12.99BT83.57-P-0001-04GH
Ventilation, function GF83.10-P-2000GH
Heater circuit function GF83.20-P-2003GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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AIR CONDITIONING, LOCATION OF COMPONENTS - GF83.30-P-0003-01GH
Location of components in passenger compartment
Fig. 50: Identifying Air Conditioning Components In Passenger Compartment (1 Of 2)

Location of components in passenger compartment
Air conditioning control module function GF83.30-P-2001GH
Refrigerant circuit function GF83.40-P-2001GH
Temperature control, function GF83.57-P-2000GH
Heater booster (ZUH), function Engine 612.963GF83.70-P-0005GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 61 © 2006 Mitchell Repair Information Company, LLC.