1997 MERCEDES-BENZ ML500 recirculation

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.

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.

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
me
Saturday, October 02, 2010 3:23:15 PMPage 51 © 2006 Mitchell Repair Information Company, LLC.

clockwise direction to the final indented position (max. cooling), the recirculation switch is bypassed and thus
the fresh air flaps closed, in order to achieve the max. interior cooling (with A/C ON).
TEMPERATURE SELECTOR WHEEL, FUNCTION - GF83.25-P-2102-01GI
Function
The desired in-car temperature is set by turning the temperature selector wheel on the AAC push-button control
module (N22).
The AAC push-button control module (N22) compares the desired temperature with the temperature in the
passenger compartment. The passenger compartment temperature is determined by the in-car temperature
sensor on the AAC push-button control module (N22) and the temperature sensor for the vent air at the center
nozzle, front and rear footwells.
Using the comparison between specified and actual values, the AAC push-button control module (N22)
determines the correct setting of the blending air flaps and actuates these. The selected temperature is reached
and maintained as quickly as possible, if warming or cooling of the interior is necessary.
TEMPERATURE SELECTOR WHEEL, LOCATION - GF83.25-P-2102-02GH
Heater depiction
The temperature selector wheel (2) is located in the heater control unit.
Fig. 48: Identifying Temperature Selector Wheel On Heater Control Unit
- Model 163
TEMPERATURE SELECTOR WHEEL, LOCATION/TASK/DESIGN/FUNCTION - GF83.25-P-2102GC
MODELS 163 up to 31.8.01, 168 up to 28.2.01
Temperature selector
wheel, locationModel 168GF83.25-P-
2102-02GC
Model 163GF83.25-P-
2102-02GH
Temperature selector The temperature selector wheel serves to preselect the

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 58 © 2006 Mitchell Repair Information Company, LLC.

TABLE OF CONTENTS, AIR CONDITIONING (TAC) FUNCTION DESCRIPTION - GF83.30-P-0999GH
MODEL 163 up to 31.8.01 with code (580) Air conditioning or Tempmatic for USA
AIR CONDITIONING CONTROL MODULE FUNCTION - GF83.30-P-2001GH
MODEL 163 up to 31.8.01 with CODE (580) Air conditioning or Tempmatic for USA
The following components are integrated into the air conditioning control module (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.
When set to the indented position "blue" 100 % recirculated air is provided.
Air distribution switch (3): with the settings: Defroster vents, footwell, center plane and intermediate settings.
Recirculation switch ( ) : 100 % recirculation without time limit, when diode illuminates.
AC button ( ): Diode illuminates,
Refrigerant compressor ON cooling mode/air dehumidification Diode is not illuminated, refrigerant compressor
OFF no air dehumidification/coolin
g mode
Air conditioning (TAC) function GF83.30-P-0001GH
Ventilation system function GF83.10-P-2000GH
Heater circuit function GF83.20-P-2003GH
Air conditioning control unit function GF83.30-P-2001GH
Refrigerant circuit function GF83.40-P-2001GH
Temperature control, function GF83.57-P-2000GH
Heater booster, functionEngine 612.963GF83.70-P-0005GH
Starting heater operation, functionEngine 612.963GF83.70-P-2000GH
Terminate heater operation functionEngine 612.963GF83.70-P-2002GH
Regulate heater operation, functionEngine 612.963GF83.70-P-2004GH
Cancel heater operation, functionEngine 612.963GF83.70-P-2005GH
Air conditioning, location of components GF83.30-P-0003-01GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 65 © 2006 Mitchell Repair Information Company, LLC.

Fig. 56: Identifying Blower Switch, Temperature Selector Wheel And Air Distribution Switch
AIR CONDITIONING CONTROL MODULE, LOCATION - GF83.30-P-2102-02GH
The AC control module (N19) is located behind the center console to the left of the evaporator housing.
Fig. 57: Identifying AC Control Module

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
AC button, location/task/function GF83.30-P-2103GH
AC control module location/task/function GF83.30-P-2102GH
All-activity module, location/task/function GF54.21-P-4110GH

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 66 © 2006 Mitchell Repair Information Company, LLC.

Fig. 62: Identifying Evaporator Housing Function - Operating Condition Blend Air Ducting
(Warm/Cold) Closed-Loop Operation
Operating condition: Blend air (warm/cold) Function
In the blend air operating status, the fresh air (A) is drawn in by the blower (5) into the evaporator housing and
routed through the dust filter (3). The air purified by the dust filter (3) is then routed through the evaporator (2)
and dried there. Some of the dried, cold and cleaned air (B) is routed through the heat exchanger (1) and some is
routed around the heat exchanger (1). This air conduction is controlled via the central setting of the blending air
flaps (6).
The air (B), which has been dried, cooled and cleaned by the heat exchanger (1) is heated up again. After
passing through the blending air flaps (6) this heated air (C) is mixed up to form blend air (D) with the dried,
cooled and cleaned air, which was routed around the heat exchanger (1). This blend air (D) is then routed via
the air outlets (E, F, M and S) into the passenger compartment. The recirculated air flap (4) is closed.
Operating condition: Air ducting "recirculation air" in cooling mode

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 71 © 2006 Mitchell Repair Information Company, LLC.

Fig. 63: Identifying Evaporator Housing Function - Operating Condition Air Ducting Recirculation Air
In Cooling Mode)
Operating condition: Cooling down "recirculation air" Function
In the cooling mode with recirculating air the blower (5) draws the recirculated air (A) from the passenger
compartment over the opened recirculated air flaps (4) into the evaporator housing and routes it through the dust
cleaner (3). The air purified by the dust filter (3) is then routed through the evaporator (2) and dried there. The
fresh air (B), which has been dried, cooled and cleaned, is subsequently routed around the heat exchanger (1).
This air conduction is controlled via the setting of the blending air flap (6).
The dried, cooled and cleaned 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).
EVAPORATOR HOUSING, TASK - GF83.30-P-2104-04GH
The evaporator housing houses the following components:
Air ducting flaps
Dust filter
Blower
Series resistor group
Evaporator
Heating system heat exchanger
Expansion valve

2001 Mercedes-Benz ML320
1998-2005 HVAC Climate Control - 163 Chassis
me
Saturday, October 02, 2010 3:23:15 PMPage 72 © 2006 Mitchell Repair Information Company, LLC.