Mercedes-Benz ML320. Service manual - part 679

 

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Mercedes-Benz ML320. Service manual - part 679

 

 

 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.

 

2001 Mercedes-Benz ML320 

1998-2005 HVAC Climate Control - 163 Chassis

  

me 

 

Fig. 84: Locating Expansion Valve 

EXPANSION VALVE, LOCATION/TASK/DESIGN/FUNCTION - GF83.40-P-2123GC 

MODEL 163 up to 31.08.01, 168 with CODE (580) Air conditioning or Tempmatic for USA  

MODEL 163 as of 01.09.01 with CODE (580a) Automatic air conditioning  

Design  

 

2001 Mercedes-Benz ML320 

1998-2005 HVAC Climate Control - 163 Chassis

  

me 

 

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 integrated in the electric fan for engine/AC and compared there with a stored 

 

Expansion valve, 
location

Model 168

GF83.40-P-2123-
02GC

   

Model 163

GF83.40-P-2123-
02GH

  Expansion valve, task

The expansion valve injects the liquid refrigerant into the 
evaporator.

 

 

Expansion valve, 
function

 

GF83.40-P-2123-
01GC

 

2001 Mercedes-Benz ML320 

1998-2005 HVAC Climate Control - 163 Chassis

  

me 

 

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 

 

2001 Mercedes-Benz ML320 

1998-2005 HVAC Climate Control - 163 Chassis

  

me 

 

 

 

 

 

 

 

 

Content   ..  677  678  679  680   ..