MERCEDES-BENZ ML350 1997 Complete Repair Manual

Fig. 2: Identifying Ventilation Function - Air Distribution Duct
Function
The ventilation system ensures:
that the windshield and windows are kept without mist.
that there is a supply of fresh air to the vehicle occupants.
that constant and pleasant temperatures are quickly achieved in the vehicle interior.
Ventilation is achieved with the assistance of the blower motor during normal operation, when vehicle is
stationary or to increase the air quantity.
Fresh air is drawn into the evaporator housing via the air inlet. Depending on the automatic air conditioning
push-button control module setting, the air is directed through the air ducts to the air vents in the interior.
The air flows out of the vehicle again through the rear vent via ventilation slots to the left and right in the area
below the rear side windows.
In recirculation mode, air is drawn out from the vehicle interior via the fresh air/recirculation flap (recirculation
setting) by the blower motor and passed to the evaporator housing.
The ventilation is essentially divided into heating operation and cooling operation.
Heating operation

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1998-2005 HVAC Climate Control - 163 Chassis
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Two main objectives are pursued in heating operation:
rapid heating and even control of in-car temperature
good visibility through windshield and front side windows
In the starting phase the headroom temperature is deliberately increased, in order to meet the passengers' initial
increased heat requirements. The temperature and the duration depend on the outside temperature and the in-car
temperature.
As far as good visibility is concerned, special control measures to accelerate defrosting of the windows are
taken during the starting phase, depending on the ambient conditions.
In closed-loop operation the footwell vents are mainly used to control the in-car temperature. The center nozzle
is fully closed. The defrosting control measures are reduced.
Cooling operation
During cooling operation the objective is to cool the interior rapidly and evenly control the temperature.
Window fogging is not usually a problem during maximum cooling operation and therefore does not require
special measures.
In the starting phase the headroom temperature is deliberately reduced. The temperature and the duration
depend on the outside temperature and the in-car temperature.
Furthermore, the cooling capacity can be reduced during subsequent operation since continuous partial
recirculating air operation can be achieved.
In closed-loop operation the center nozzles are mainly used to control the in-car temperature.
Bi-level operation (2-level operation)
In bi-level operation the temperature of the interior is controlled by a combination of the footwell nozzles and
the center nozzles.
The objective is to create stratification , which gives the passengers warm feet and a cooler head .
The air distribution shifts in the direction of heating or cooling operation depending on the controller status
trend.
Rear compartment ventilation
The rear compartment nozzles are supplied with temperature-controlled air by the front compartment automatic
air conditioning. The rear compartment nozzle outlet temperature can therefore not be separately controlled.
The air quantity and the air distribution are available as adjustable parameters. The passengers in the rear can
control the ventilation themselves usin
g appropriate buttons.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Saturday, October 02, 2010 3:23:14 PMPage 8 © 2006 Mitchell Repair Information Company, LLC.

In automatic mode the air quantity and the air distribution are controlled depending on the status of the
automatic air conditioning.
AIR INLET, LOCATION - GF83.10-P-2100-01GH
The air inlet (1) is located at the bottom of the windshield.
Air inlet, location/function GF83.10-P-2138GC
Air ducts, location/task/design GF83.10-P-2139GH
Rear vent, location/task/function GF83.10-P-2143GC
Defroster vent, location/task/function GF83.10-P-2144GC
Center nozzle, location/task/function GF83.10-P-2149GC
Lateral nozzle, location/task/function GF83.10-P-2150GC
Rear nozzle position/task//function GF83.10-P-2151GI
Front footwell air outlet, location/task/function GF83.10-P-2145GC
Rear footwell air outlet, location/task/function GF83.10-P-2146GI
Blower motor, position/task//function GF83.10-P-2170GI
Rear blower motor, position/task/design/function GF83.10-P-2168GI
Blower regulator, location / task / function GF83.10-P-2141GI
Rear ventilation electronic blower regulator location/task/function GF83.10-P-2176GI
Combination filter, location/task/function GF83.10-P-2128GI
Defroster vent flap actuator motor, location/task/ function GF83.10-P-2175GI
Footwell flap actuator motor, location / task / function GF83.10-P-2132GI
Center outlet flap actuator motor, location / task / function GF83.10-P-2172GI
Rear shutoff flap actuator motor, location / task / function GF83.10-P-2171GI
Rear air distribution flap actuator motor, location / task / function GF83.10-P-2173GI
Fresh air/recirculation flap, location / task / function GF83.20-P-2111GC
Fresh air/recirculation flap actuator motor, location / task / function GF83.30-P-2116GC
Blending air flap actuator motor, location / task / function GF83.57-P-2112GI
Blower switch, location/task/design/function GF83.25-P-2100GI
Air distribution switch, location/task/design/ function GF83.25-P-2101GI
Recirculating air push-button, location/task/ function GF83.40-P-2145GI
Air conditioner housing, location / task / design / function GF83.40-P-2105GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Saturday, October 02, 2010 3:23:14 PMPage 9 © 2006 Mitchell Repair Information Company, LLC.

Fig. 3: Identifying Air Inlet
AIR DUCT LOCATIONS - GF83.10-P-2101-01GH
The lateral nozzle and side window defroster nozzle (3) air ducts are on the left and right below the instrument
panel.
The windshield defroster nozzle air duct (2) is on top of the heater/evaporator housing (front center) below the
instrument panel.
The center nozzle air duct (1) is on top of the heater box/evaporator housing behind the center nozzle.
The front footwell air duct (4) is integrated in the heater/evaporator housing.
The rear footwell air duct (5) is below the center console.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 4: Identifying Air Duct (Up To 31.08.01)
AIR DUCT LOCATIONS - GF83.10-P-2101-01GI
The lateral nozzle and side window defroster nozzle (3) air ducts are on the left and right below the instrument
panel.
The windshield defroster nozzle air duct (2) is on top of the evaporator housing (front center) below the
instrument panel.
The center nozzle air duct (1) is on top of the evaporator housing behind the center nozzle.
The front footwell air duct (4) is integrated in the heater/evaporator housing.
The rear compartment air duct (5) is located below the center console.
The rear footwell air duct (6) is at the bottom next to the rear blower behind the center console.

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 5: Identifying Air Duct (As Of 1.09.01)
BLOWER, LOCATION - GF83.10-P-2102-01GH
The blower (M2) is below the instrument panel to th e bottom right of the heater box/evaporator housing (3).

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 6: Identifying Blower And Heater Box/Evaporator Housing
BLOWER, FUNCTION - GF83.10-P-2102-02GH
Function
Different control voltages are provided at the blower (M2) via the series resistors depending on the blower
switch setting. This produces different blower (M2) speeds.
BLOWER, LOCATION / TASK / DESIGN / FUNCTION - GF83.10-P-2102GC
MODEL 163 up to 31.8.01, 168
BLOWER CONTROLLER FUNCTION - GF83.10-P-2103-01GI
Function
The blower switch passes on a control voltage (0 - 6 V) to the blower regulator (A32n1) via the AAC push-
button control module (N22) and the AC bus. Depending on the control voltage which is present, this then
regulates the blower motor operating voltage (0 - 12 V). This facilitates blower speed control of 0-100 %.
The Auto button can also be used to select
( ) automatic mode.
Pin assignment of series resistor assembly
R14Assigned
resistorBlower switch
settingBlower (M2) control
voltage
Pin 1R3Blower level 310V
Pin 2R2+R3Blower level 28V
Pin 3R1+R2+R3Blower level 14V
Pin 4NoneBlower level 412V
Blower,
locationModel 168GF83.10-P-
2102-01GC
Model 163GF83.10-P-
2102-01GH
Blower,
taskIn fresh air mode the blower (M2) draws in fresh air, and in recirculating air
mode it draws in air from the vehicle interior into the heater or evaporator
housing via the recirculating air flap.

Blower
designThe blower (M2) is designed as a twin-pipe radial blower.
Blower,
functionModel 168GF83.10-P-
2102-02GC
Model 163GF83.10-P-
2102-02GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Saturday, October 02, 2010 3:23:14 PMPage 13 © 2006 Mitchell Repair Information Company, LLC.

The blower regulator then controls the blower motor operating voltage, depending on the actual measured in-car
temperature and the selected target temperature
(0-12 V). This facilitates blower speed control of 0-100 %.
DUST FILTER, LOCATION - GF83.10-P-2104-01GH
The dust filter (1) is behind the instrument panel bottom section at the passenger side in the heater/evaporator
housing.
Fig. 7: Identifying Dust Filter

REAR VENTILATION, FUNCTION - GF83.10-P-2105-01GC
Function
The louvered-type flaps in the rear vent open from the pressure of the air flowing through the vehicle and allow
it to exit.
If a vacuum is present in the vehicle, as happens when driving with a window or the sliding roof open, the flaps
close automatically due to the force of gravity. This prevents exhaust gases, dust and moisture from being
sucked in.
REAR VENTILATION, LOCATION - GF83.10-P-2105-02GH
The rear vents (1) are located on the left and right behind the rear bumper.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Saturday, October 02, 2010 3:23:14 PMPage 14 © 2006 Mitchell Repair Information Company, LLC.

Fig. 8: Identifying Rear Vents
DEFROSTER NOZZLE, LOCATION - GF83.10-P-2106-01GH
Windshield defroster nozzle
The windshield defroster nozzle (1) is located in the instrument panel below the windshield.
Fig. 9: Identifying Windshield Defroster Nozzle

Side window defroster nozzles
The side window defroster nozzles (1) are located on the left and ri
ght in the instrument panel.

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1998-2005 HVAC Climate Control - 163 Chassis
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Fig. 10: Identifying Side Window Defroster Nozzles
CENTER NOZZLE, FUNC TION - GF83.10-P-2107-01GH
Function
The dial on the left allows the left and middle outlets in the center nozzle to be opened and closed infinitely
separately from the right outlet which is controll ed in the same manner by the dial on the right.
The air exit direction can be adjust ed upward, downward, to the left, right or center with three separately
adjustable sets of louvers.
Cooled/heated air exits from the center nozzle (1).
Fig. 11: Identifying Center Nozzle


2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
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Saturday, October 02, 2010 3:23:14 PMPage 16 © 2006 Mitchell Repair Information Company, LLC.