air condition MERCEDES-BENZ ML320 1997 Complete Repair Manual

(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.

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.

Fig. 37: Identifying Heater Box Function - Operating Condition Heating
Operating condition: Heating Function
In the heating operating status, the fresh air (A) is drawn in by the blower (5) into the heater housing and routed
through the dust filter (3). The fresh air (B), which is cleaned by the dust filter (3), is subsequently conducted
through the heat exchanger (1). This air conduction is controlled via the setting of the blending air flaps (6).
The cleaned fresh air (B) is heated up by the heat exchanger (1). The warm air (C) is conducted via the air
outlets (E, F, M and S) into the vehicle interior.
The recirculated air flap (4) is closed.
Operating condition: No heating

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 47 © 2006 Mitchell Repair Information Company, LLC.

Fig. 38: Identifying Heater Box Function - Operating Condition No Heating
Operating condition: No heating Function
In the "no heating" operating status, the fresh air (A) is drawn in by the blower (5) into the heater housing and
routed through the dust filter (3).
The fresh air (B), which is cleaned by the dust filter (3), is subsequently routed around the heat exchanger (1).
This air conduction is controlled via the setting of the blending air flaps (6).
The cleaned fresh air (B) is routed directly into the passenger compartment via the air outlets (E, F, M and S).
The recirculated air flap (4) is closed.
Operating condition: No "recirculated air" heating

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 48 © 2006 Mitchell Repair Information Company, LLC.

Fig. 39: Identifying Heater Box Function - Operating Condition No Recirculated Air Heating
Operating condition: No "recirculating air" heating Function
In the no "recirculated air" heating mode the blower (5) draws the recirculated air (A) from the passenger
compartment over the opened recirculated air flaps (4) into the heater housing and routs it through the dust
cleaner (3). The recirculated air (B), which is cleaned by the dust filter (3), is subsequently routed around the
heat exchanger (1). This air conduction is controlled via the setting of the blending air flaps (6).
The cleaned recirculated air (B) is routed directly into the passenger compartment via the air outlets (E, F, M
and S).
The supply of fresh air is cut off by the recirculated air flap (4).
HEATER HOUSING TASK - GF83.20-P-2103-03GC
The heater housing serves to house the following components
Air ducting flaps
Dust filter
Blower
Series resistor group
Heating system heat exchanger
PTC heater booster (in model 168 with engines OM 668.940/941 as of 01.03.01)
Fresh air/recirculated air flap actuator (with model 168 as of 01.03.01)

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 49 © 2006 Mitchell Repair Information Company, LLC.