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Fig. 81: Identifying Condenser 
EVAPORATOR, FUNCTION - GF83.40-P-2121-01GC 
Function  
The refrigerant, which is under high pressure, is injected into the evaporator. The evaporator is a disk-type 
evaporator made of soldered semicircular disks with louvered corrugated fins by the Valeo company for model 
168 and the Denso company for model 163. 
The heat that is required for evaporation is extracted from the air flowing past the evaporator, which cools 
down. The soldered semicircular disks with louvered corrugated fins or slats provide a large evaporation surface 
and guarantee rapid heat exchange. 
The moisture that condenses when the air cools is led to the outside via condensation drain hoses. 
The condensation also binds the solids in the air and therefore cleans it. 
EVAPORATOR, LOCATION - GF83.40-P-2121-02GH 
The evaporator (1) is located in the air conditioning box.
 
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Fig. 82: Locating Evaporator 
EVAPORATOR, LOCATION/PURPOSE/DESIGN/FUNCTION - GF83.40-P-2121GC 
MODELS 163, up to 31.8.01, 168 with code (580) Air conditioning or Tempmatic for USA  
MODELS 163 as of 1.9.01 with code (580a) Automatic air conditioning  
FLUID RESERVOIR FUNCTION - GF83.40-P-2122-01GI 
Function  
The liquefied refrigerant enters the fluid reservoir under pressure and flows through a stainless-steel fabric layer 
to the filter block. The filter block's pores are matched exactly to the molecular size of the refrigerant. Thus the 
refrigerant can flow through the filter block. 
All other matter, primarily water, is held back by this molecular filter and deposited. The cleansed refrigerant 
then flows through a rising pipe to the expansion valve.
 Evaporator, 
locationModel 168GF83.40-P-2121-
02GC
  Model 163GF83.40-P-2121-
02GH
 Evaporator, 
purposeThe evaporator is used to cool, dehumidify and clean the interior 
air. 
 Evaporator, 
designThe evaporator is a disk-type evaporator made of soldered 
semicircular disks with louvered corrugated fins. 
 Evaporator, 
function GF83.40-P-2121-
01GC
 
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1998-2005 HVAC Climate Control - 163 Chassis  
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 Whenever the system is opened, the fluid reservoir should be replaced because of the water which has 
collected there in the meantime. 
EXPANSION VALVE, FUNCTION - GF83.40-P-2123-01GC 
Function  
When the refrigerant compressor is switched on the pressure in the evaporator drops, thereby causing the 
diaphragm (1) to curve downwards. The control valve (3) follows the movement of the diaphragm and presses 
the ball (4) out of its seating against the spring (5). The opened valve enables the refrigerant to be sprayed into 
the evaporator. 
As the diaphragm movement (1) is dependent on both the intake pressure and the temperature at the evaporator 
outlet, only the specific quantity of refrigerant, as required for optimum vaporization, is injected. 
Fig. 83: Identifying Expansion Valve Components
 
EXPANSION VALVE, LOCATION - GF83.40-P-2123-02GH 
The expansion valve (1) is located on the right at the rear in the engine compartment next to the battery.
 
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Fig. 84: Locating Expansion Valve 
EXPANSION VALVE, LO CATION/TASK/DESIGN/FUNCTION - GF83.40-P-2123GC 
MODEL 163 up to 31.08.01, 168 with CODE (580) Ai r conditioning or Tempmatic for USA   
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning     
Design    
 
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1998-2005 HVAC Climate Control - 163 Chassis  
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Fig. 85: Identifying Expansion Valve Design
REFRIGERANT PRESSURE SENSOR, FUNCTION - GF83.40-P-2126-01GH 
Function  
Shutting off the refrigerant compressor  
The refrigerant pressure sensor (B12) sends the current value to the All Activity Module (N10). The All 
Activity Module (N10) compares this input information with stored values and actuates the refrigerant 
compressor. 
At the following values, the refrigerant compressor is switched on or off: 
refrigerant pressure > 3 bar = refrigerant compressor ON  
refrigerant pressure < 2 bar = refrigerant compressor OFF  
refrigerant pressure < 26 bar = refrigerant compressor ON  
refrigerant pressure > 30 bar = refrigerant compressor OFF  
Cut-in of the auxiliary fan (engines 111.977 and 112.942)  
The pressure value received from the refrigerant pressure sensor (B12) is recorded by the All Activity Module 
(N10) and compared there with a stored value. 
As of 12/99, the Extended Activity Module (EAM, N10/1) assumes this task from the All Activity Module 
(N10). 
At the following values, the auxiliary fan (M4m1, M4m2) is switched on or off: 
refrigerant pressure > 16 bar = auxiliary fan ON  
refrigerant pressure <12 bar = auxiliary fan OFF  
Cut-in of the electric fan for engine/AC (engines 113.942/981 and 612.963)  
The pressure value received from the refrigerant pressure sensor (B12) is recorded by the All Activity Module 
(N10), sent to the control module inte
grated in the electric fan for engine/AC and compared there with a stored 
 Expansion valve, 
locationModel 168GF83.40-P-2123-
02GC
  Model 163GF83.40-P-2123-
02GH
 Expansion valve, taskThe expansion valve injects the liquid refrigerant into the 
evaporator. 
 Expansion valve, 
function GF83.40-P-2123-
01GC
 
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1998-2005 HVAC Climate Control - 163 Chassis  
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value. 
At the following values the electric fan for engine/AC (M4/7) is switched on or off: 
refrigerant pressure > 20 bar = electric fan for engine/AC ON  
refrigerant pressure <12 bar = electric fan for engine/AC OFF  
REFRIGERANT PRESSURE SENSOR, LOCATION - GF83.40-P-2126-02GH 
The refrigerant pressure sensor (B12) is located at the front left in the engine compartment at the high-pressure 
line (8) between the refrigerant compressor (A9) and the capacitor (7). 
Fig. 86: Identifying Refrigerant Pressure Sensor
 
DEFROSTER BUTTON, FUNCTION - GF83.40-P-2139-02GI 
Function  
Pressing the defroster button (  ) initiates the defrost function. 
Function feedback takes place by means of a yellow LED. 
The defrost function works according to the following logic: 
the heating power is regulated using the outside temperature  
the entire air flow is directed at the windshield and the front side windows, and the defroster nozzles are 
 
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1998-2005 HVAC Climate Control - 163 Chassis  
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opened.  
the injected air is dehumidified, Reheat mode  
blend air flaps controlled  
footwell nozzles closed  
DEFROSTER BUTTON, LOCATION / TASK / FUNCTION - GF83.40-P-2139GI 
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning  
Fig. 87: Identifying Blower Switch And Defroster Button
 
BLOWER BUTTON POSITION/TASK/FUNCTION - GF83.40-P-2144GI 
MODEL 163 as of 01.09 01 with CODE (580a) Automatic air conditioning in the rear ventilation control 
panel  
 Defroster button, 
locationThe defroster button (  ) is located in the center in the upper half of 
the blower switch (1) on the AAC push-button control module (N22). 
 Defroster button, 
purposeThe defroster button (  ) starts the defroster function. 
 Defroster button, 
function GF83.40-P-
2139-02GI
 
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1998-2005 HVAC Climate Control - 163 Chassis  
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Fig. 88: Identifying Blower Button 
RECIRCULATING AIR PUSH-BUTTON, LOCATION/TASK/FUNCTION - GF83.40-P-2145GI 
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning  
Fig. 89: Identifying Recirculating Air Push
-button And Blower Switch 
AUTO BUTTON, LOCATION / TASK / FUNCTION - GF83.40-P-2147GI 
MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning
 Blower button, 
locationThe blower button (  ) is located in the center in the rear 
ventilation control panel. 
 Blower button, 
taskThe blower button (  ) is used to cut in the blower motor for 
fresh air and recirculating air operation. 
 Blower button, 
function GF83.40-P-2100-
01GI
 Recirculating air 
push-button, positionThe recirculating air push-button (  ) is located in the center 
in the lower half of the blower switch (1) on the AAC push-
button control module (N22).
 
 Recirculating air 
push-button, task
The recirculating air push-button (  ) is used to operate the 
fresh air/recirculated air flap to permit air to be directed out of the 
vehicle interior. 
Function feedback takes place by means of a red LED.
 
 Recirculating air 
push-button, function GF83.40-P-
2102-01GI
 
2001 Mercedes-Benz ML320 
1998-2005 HVAC Climate Control - 163 Chassis  
me  
Saturday, October 02, 2010 3:23:16 PMPage 108 © 2006 Mitchell Repair Information Company, LLC.