MERCEDES-BENZ ML350 1997 Complete Repair Manual

Fig. 29: Locating Center Outlet Flap Actuator Motor
REAR AIR DISTRIBUTION FLAP ACTUATOR MOTOR FUNCTION - GF83.10-P-2173-01GI
Function
Pressing the rear compartment air distribution button ( ) on the AAC push-button control module (N22)
actuates the air distribution flap actuator motor (M2/21) via the AC bus. The air distribution flap actuator motor
(M2/21) therefore controls the air distribution flap, which opens and controls the air supply to the rear blowout
ducts.
If a problem exists, it is possible to retrieve and verify the defined end positions by means of the Diagnosis
Assistant System (DAS) (valuation trip).
After replacing an actuator motor an adjustment run must be performed using the Diagnosis Assistant System
Center outlet flap
actuator motor locationThe center outlet flap actuator motor (M2/22) is to the right of
the center nozzle air duct, below the instrument panel.
Center outlet flap
actuator motor taskThe center outlet flap actuator motor (M2/22) operates the
center outlet flap for controlling the flow of air to the center
nozzle.

Center outlet flap
actuator motor function GF83.10-P-
2172-01GI
NOTE: All actuator motors are identical.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 37 © 2006 Mitchell Repair Information Company, LLC.

(DAS), i.e. the end positions flap OPEN and SHUT are defined and retained.
REAR AIR DISTRIBUTION FLAP ACTUATOR MOTOR, LOCATION/TASK/FUNCTION - GF83.10-P-2173GI
MODEL 163 as of 1.9.01 with CODE (580a) Automatic air conditioning
Fig. 30: Locating Rear Air Distribution Flap Actuator Motor

DEFROSTER VENT FLAP ACTUATOR MOTOR, FUNCTION - GF83.10-P-2175-01GI
Function
Pressing the defroster button ( ) on the AAC push-button control module actuates the defroster vent flap
actuator motor (M2/8) via the air conditioner bus. The defroster vent flap actuator motor (M2/8) controls the
defroster nozzle flaps, which adopt the followin
g positions, according to requirements:

Rear air distribution
flap actuator motor
locationThe rear air distribution flap actuator motor (M2/21) is to the left
of the rear blower housing, behind the rear compartment nozzle.

Rear air distribution
flap actuator motor
taskThe rear air distribution flap actuator motor (M2/21) operates the
rear air distribution flap for controlling the flow of air to the rear
compartment nozzle and the rear footwell air vents.


Rear air distribution
flap actuator motor
function
GF83.10-P-
2173-01GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 38 © 2006 Mitchell Repair Information Company, LLC.

Defrost function
Defroster nozzle flap open 100 %.
System switched off
Defroster nozzle flap open 100 % (This limp-home capability ensures that the windshield will not fog up even
when a malfunction has occurred)
Defroster nozzle flap control via the push-button control module
(Clock type switch setting of air distribution switch)
If a problem exists, it is possible to retrieve and verify the defined end positions by means of the diagnosis
assistant system (DAS) (valuation trip).
After replacement of an actuator motor it is necessary for an adjustment run to be performed using the diagnosis
assistant system (DAS), i.e. the end positions flap OPEN and SHUT are defined and retained.
DEFROSTER VENT FLAP ACTUATOR MOTOR, LOCATION/TASK/FUNCTION - GF83.10-P-2175GI
Model 163 as of 1.9.01 with code (580a) Automatic air conditioning
1 o'clock 2 o'clock 3 o'clock 4 o'clock 5 o'clock6 o'clock
85% 68% 50% 32% 17%
0%
7 o'clock 8 o'clock 9 o'clock 10 o'clock 11 o'clock
12 o'clock
0 % 0 % 0 % 32 % 70 %
100 %
NOTE: All actuators are identical.

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 39 © 2006 Mitchell Repair Information Company, LLC.

Fig. 31: Identifying Defroster Vent Flap Actuator Motor
ELECTRONIC BLOWER CONTROL UNIT, REAR VENTILATION, FUNCTION - GF83.10-P-2176-01GI
Function
The blower push-button ( ) in the rear ventilation control panel (N72/2s3) is used to send a control voltage
to the rear electronic blower regulator (N29/2). Depe nding on the control voltage (0 - 6 V) present, this then
regulates the operating voltage (0 -12 V) for the rear blow er motor (M2/1). This facilitates blower speed control
of 0-100%.
Automatic operation, function
By pressing the Auto button ( ) in th e rear ventilation control panel the control of the rear electronic blower
re
gulator and thus that of the rear blower motor is governed by the AAC push-button control module.

Defroster vent flap
actuator motor,
locationThe defroster vent flap actuator moto r (M2/8) is located at the left
side of the air conditioner housing.
Defroster vent flap
actuator motor, taskThe defroster vent flap actua tor motor (M2/8) operates the
defroster vent flaps for air flow control to the windshield defroster
vent and side window defroster vents.


Defroster vent flap
actuator motor,
function
GF83.10-P-
2175-01GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 40 © 2006 Mitchell Repair Information Company, LLC.

REAR ELECTRONIC BLOWER REGULATOR, LOCATION/TASK/FUNCTION - GF83.10-P-2176GI
Model 163 as of 1.9.01 with code (580a) Automatic air conditioning
Fig. 32: Identifying Rear Electronic Blower Regulator

HEATER FUNCTION - GF83.20-P-0002GH
MODEL 163 up to 31.8.01
Function
The heater enables a pleasant interior climate for the vehicle passengers in the event of different weather
conditions.
A nominal temperature is preset at the heater push-button control module temperature selector wheel. This
setting is transmitted to the blending air flaps in the heater housing via a cable and an actuation mechanism.
Rear electronic blower
regulator, locationThe rear electronic blower regulator (N29/2) is located behind
the rear nozzle below the center console.
Rear electronic blower
regulator, taskThe rear electronic blower regulator (N29/2) controls the rear
blower motor (M2/1) voltage supply depending on the relevant
blower level setting.

Rear electronic blower
regulator, function GF83.10-P-
2176-01GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 41 © 2006 Mitchell Repair Information Company, LLC.

Control is then carried out there as follows:
Temperature selector wheel MAX setting (full heater output)
Due to the setting of the blending air flaps, the drawn in air is routed through the heat exchanger. Heated
cooling water generally flows through this, as a result of which the passing air is heated. The temperature-
controlled air is guided into the vehicle interior via the various air outlets.
Temperature selector wheel MIN setting (no heater output)
In this setting, the blending air flaps block the route to the heat exchanger. The drawn in fresh air is guided
directly to the air outlets and therefore into the vehicle interior.
HEATER FUNCTIONAL DESCRIPTION TABLE OF CONTENTS - GF83.20-P-0998GH
MODEL 163 up to 31.8.01 except CODE (580) Air conditioning or Tempmatic for USA
Ventilation system function GF83.10-P-2000GH
Heater circuit function GF83.20-P-2003GH
Heater controls, function GF83.20-P-2004GH
Heater function GF83.20-P-0002GH
Ventilation system function GF83.10-P-2000GH
Heater circuit function GF83.20-P-2003GH
Heater controls, function GF83.20-P-2004GH
Air inlet, location/function GF83.10-P-2138GC
Air ducts, location/task/design GF83.10-P-2139GH
Blower, location/task/design/function GF83.10-P-2102GC
Series resistor group, location/task/function GF83.10-P-2161GC
Dust filter, location/task/function GF83.10-P-2142GH
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
Front footwell air outlet, location/task/function GF83.10-P-2145GC
Rear footwell air outlet, location/task/function GF83.10-P-2146GC
Heating system heat exchanger, location/ purpose/function GF83.20-P-2108GC
Fresh air/recirculated air flap, location/task/ function GF83.20-P-2111GC
Fresh air/recirculated air flap actuator, location/ task/function GF83.30-P-2116GC
Blower switch, location/task/design/function GF83.25-P-2100GC
Air distribution switch, location/task/design/ function GF83.25-P-2101GH
Temperature selector wheel, location/task/ design/function GF83.25-P-2102GC
Air recirculation switch, location/task/design/ function GF83.10-P-2117GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 42 © 2006 Mitchell Repair Information Company, LLC.

HEATER CIRCUIT FUNCTION - GF83.20-P-2003GH
MODEL 163
Fig. 33: Identifying Heater Circuit Function

Function
The coolant pump (5) pumps cold coolant through the engine. The coolant absorbs the engine's heat and
becomes heated. The heated coolant is then conducted through the heat exchanger (2). The air blowing by the
heat exchanger (2) is heated and conducted into the vehicle interior.
The coolant is routed over the coolant return (A) and the heating water circulation pump (6) back to the coolant
pump (5).
By far the greater percentage of the coolant does not flow through the heat exchanger (2), but from the engine to
the coolant thermostat (4). Depending on the water temperature, this conducts the water through the radiator (3)
or directly to the coolant pump (5).
HEATER CONTROLS, FUNCTION - GF83.20-P-2004GH
Heater housing position/task/function GF83.20-P-2110GC
Heating system heat exchanger, location/ purpose/function GF83.20-P-2108GC
Heater water circulation pump, location/task/ functionas of 1.09.01GF83.20-P-2109GI

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 43 © 2006 Mitchell Repair Information Company, LLC.

Model 163 up to 31.8.01
The following components are integrated into the heater control unit (S98):
Blower switch (1): with 0 setting and 4 levels.
The blower switch (1) is not available as an individual part.
Temperature selector wheel (2): with the "Blue", non-heating setting and the continuously variable heater
setting.
Air distribution switch (3): with the settings: Defroster vents, footwe ll, center plane and intermediate settings.
Recirculation switch ( ): Functions if diode is illuminated.
Fig. 34: Identifying Blower Switch, Selector Wheel And Air Distribution Switch On Heater Control Unit

HEATER CORE, FUNCTI ON - GF83.20-P-2101-01GC
Function
The heater coolant flows through the heater core. The he at is conducted to the outside by the aluminum tubes
and fins.
This heats up the air flowing through on the way to the vari ous defroster, vent and heater nozzles in the vehicle
passenger compartment.
HEATING SYSTEM HEAT EXCHANGE R, LOCATION - GF83.20-P-2101-02GH
The heater core (1) is located behind the instrument panel in the heater/ A/C housing.
Blower switch, location/task/design/function GF83.25-P-2100GC
Air distribution switch, locat ion/task/design/ function GF83.25-P-2101GH
Temperature selector wheel, location/task/ design/function GF83.25-P-2102GC
Air recirculation switch, loca tion/task/design/ function GF83.10-P-2117GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 44 © 2006 Mitchell Repair Information Company, LLC.

Fig. 35: Identifying Heater Core
HEATING WATER CIRCULATION PUMP FUNCTION - GF83.20-P-2102-01GI
Function
The quantity of coolant delivered to the heat exchanger when the engine is running is dependent on the coolant
pump. The heating water circulation pump ensures that a constant and bubble-free flow of water is present at
the heat exchanger during residual engine heat utilization, even at low engine speeds.
Initialization of the heating water circulation pump is carried out via the AAC push-button control module
(N22).
Switch-on conditions
Ignition ON
Stationary heater/ON
Enable conditions at residual engine heat complied with
Special conditions
At ambient temperatures of less than -20°C several starting attempts are made, in order to ensure that the
heating water circulation pump goes into operation.
To this end the heating water circulation pump is switched off in intervals of 1 minute for 5 seconds, until the
coolant or blow-out temperature is +20°C higher than the ambient temperature.
Switch-off conditions
Ignition OFF and overshoot time expired
Stationary heater OFF
Residual engine heat OFF and overshoot time expired
Enable conditions at residual engine heat no longer complied with
Enable conditions at residual engine heat

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 45 © 2006 Mitchell Repair Information Company, LLC.

The heating water circulation pump runs in any event 1 minute after starting residual engine heat operation. The
overshoot conditions at least will be fulfilled.
Overshoot conditions
Coolant temperature 100°C --> overshoot time 5 minutes
Coolant temperature >100°C --> overshoot time 10 minutes
HEATER HOUSING POSITION - GF83.20-P-2103-01GH
The heater housing (1) is located beneath the instrument panel.
Fig. 36: Identifying Heater Housing

HEATER BOX FUNCTION - GF83.20-P-2103-02GH
Operating condition: Heating

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 46 © 2006 Mitchell Repair Information Company, LLC.