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Operating condition: Air ducting in heating mode
Fig. 60: Identifying Evaporator Housing Function 
- Operating Condition Air Ducting In Heating Mode 
Operating condition: HEATING Function  
In the heating 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. The fresh air (B), which has been dried, cooled and cleaned, is subsequently routed through the 
heat exchanger (1). This air conduction is controlled via the setting of the blending air flaps (6). 
The fresh air (B), which has been dried, cooled and cleaned, is heated up again in 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: Air ducting in cooling mode
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
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Fig. 61: Identifying Evaporator Housing Function - Operating Condition Air Ducting In Cooling Mode) 
Operating condition: cooling Function  
In the cooling 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. 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 flaps (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 recirculated air flap (4) is closed. 
Operating condition: Blend air ducting (warm/cold) closed-loop operation
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
me  
Saturday, October 02, 2010 3:23:15 PMPage 70 © 2006 Mitchell Repair Information Company, LLC.  
     
        
        Page 3315 of 4133

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.  
     
        
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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.  
     
        
        Page 3317 of 4133

Blending air flap actuator  
Recirculated air flap actuator motor  
Electric heater booster (for engine 612.963 only) and therefore forms a complete unit.  
The evaporator housing distributes the air that is required to ventilate the vehicle to the relevant air ducts and 
vents depending on the required interior temperature. 
The air ducting depends on various operating conditions such as: 
Heating mode  
Cooling mode  
Blend air mode (cold/warm)  
Cooling air mode with recirculated air  
FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTOR, POSITION - GF83.30-P-2105-01GC 
The fresh air/recirculated air flap actuator motor (M16/7) is located on the A/C housing between the two fresh 
air/recirculated air flaps. 
Fig. 64: Identifying Fresh Air/Recirculated Air Flap Actuator Motor
 
FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTOR, POSITION - GF83.30-P-2105-01GH 
The fresh air/recirculated air flap actuator motor (M39) is located at the side of the air intake housing on the 
evaporator housin
g. 
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
me  
Saturday, October 02, 2010 3:23:15 PMPage 73 © 2006 Mitchell Repair Information Company, LLC.  
     
        
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Fig. 65: Identifying Fresh Air/Recirc ulated Air Flap Actuator Motor 
FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR MOTO R, FUNCTION - GF83.30-P-2105-02GH 
Function   
The fresh air/recirculated air flap actuator motor (M39)   is controlled via the recirculation air switch (  ) and  
when the temperature selector switch is set to   max. cooling output in the control module (S98).  
Recirculated air mode (100 % recirculated air)     
In the recirculated air mode the supply   of fresh air is closed by the fresh air/recirculated air flap actuator motor  
(M39) and simultaneously the recirculated   air supply opened without any time limit.  
Fresh air mode (100 % fresh air)     
In the fresh air mode the supply of fresh air is opened by th  e fresh air/ recirculated air flap actuator motor (M39)  
and simultaneously the recirculated air   supply closed without any time limit.  
Auxiliary function at   air conditioning (TAC)    
When, in the cooling mode, the temperat  ure selector wheel is set to max. cooling (position indented blue) then  
at the same time the fres  h air/recirculated air flap actuator moto r (M39) is controlled and switched to  
recirculation air wi  thout time limit. 
FRESH AIR/RECIRCUL ATED AIR FLAP ACTUATOR, FU NCTION - GF83.30-P-2105-02GI 
Function   
Pressing the recirculating air push-  button (  ) on the AAC push-button control module (N22) actuates the  
fresh air/recirculated air   flap actuator motor (M2/5) via the air conditioner bus.  
In recirculation mode, the recircul  ation air supply is closed off by th e fresh air/recirculated air flap.  
In fresh air mode, the fresh air supply is ope  ned by the fresh air/ recirculated air flap. 
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
me  
Saturday, October 02, 2010 3:23:15 PMPage 74 © 2006 Mitchell Repair Information Company, LLC.  
     
        
        Page 3319 of 4133

Control of fresh air/recirculated air flap via the AAC push-button control module (N22)  
When the recirculating air push-button is pressed (  ) on the AAC push-button control module the system is 
switched by means of the fresh air/recirculated air flap actuator motor straight to 100 % recirculation air. This is 
displayed by the function LED. 
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. 
AIR CONDITIONING FLUID RESERVOIR, LOCATION - GF83.30-P-2106-01GH 
The fluid reservoir (6) is located in the left front of the engine compartment, next to the condenser. 
Fig. 66: Identifying Air Conditioning Fluid Reservoir And Associated Components
 
AIR CONDITIONING FLUID RESERVOIR, FUNCTION - GF83.30-P-2106-02GC 
Function  
NOTE: The recirculated air function can be terminated after a set time-out in 
accordance with country specifications.
NOTE: All actuators are identical.
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
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        Page 3320 of 4133

The liquefied refrigerant is routed under pressure into the fluid reservoir and flows through a stainless steel 
meshing to the filter block. The pores in the filter block are matched precisely to the refrigerant's molecular size. 
Thus the refrigerant can flow through the filter block. 
All other matter, primarily water, is held back by this molecular filter and deposited. The cleaned refrigerant 
flows over a rising pipe to the expansion valve. 
 Whenever the system is opened, the fluid reservoir should be replaced because of the water which has 
collected there in the meantime. 
ALL-ACTIVITY MODULE, LOCATION - GF83.30-P-2108-02GH 
The all-activity module (AAM) (N10) is located in the left-hand side of the engine compartment. It is plugged 
on from below to the fuse and relay module (F1). 
Fig. 67: Identifying All
-Activity Module And Relay Module 
FRESH AIR/RECIRCULATED AIR FLAP ACTUATOR, LOCATION/TASK/FUNCTION - GF83.30-P-2116GC 
MODELS 163 up to 31.8.01, 168 up to 28.2.01 with CODE (580) Air conditioning or Tempmatic for USA 
MODEL 163 as of 1.9.01 with code (580a) Automatic air conditioning  
Shown on model 163 as of 1.09.01  
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
me  
Saturday, October 02, 2010 3:23:15 PMPage 76 © 2006 Mitchell Repair Information Company, LLC.