GF83.40-P-2005LE Automatic Air Conditioning Refrigerant Circuit, Function

GF83.40-P-2005LE Automatic Air Conditioning Refrigerant Circuit, Function

Component Identification:

Function requirements, general
^ Circuit 61
^ Automatic air conditioning switched on

The circuit status of circuit 61 is made available on the chassis CAN by the CDI control unit (N3/9) (for diesel engine) or by the ME-SFI [ME] control unit (N3/10) (for gasoline engine) and forwarded from the central gateway control unit (N93) via the interior CAN to the AAC [KLA] control unit (N22/1).

Automatic air conditioning refrigerant circuit, general
Regulation of the automatic air conditioning refrigerant circuit is performed via the AAC [KLA] control unit.
Depending on the setting at the upper control panel control unit (N72/1), at the front central operating unit (A40/9) or at the rear air conditioning control unit (N22/4) (on model 221 with code (582) Rear air conditioning), the air in the vehicle interior is cooled by the automatic air conditioning refrigerant circuit.

The automatic air conditioning refrigerant circuit mainly consists of the following components:
- Refrigerant compressor
- Condenser
- Fluid reservoir
- Expansion valve
- Evaporator
- Hoses and pipelines

The individual components of the refrigerant circuit are interconnected through hoses and pipelines and form a closed system.

The automatic air conditioning refrigerant circuit consists of the following functional components:
^ Function sequence, high-pressure side
^ Function sequence, low-pressure side

The separation points for this are the valve plate at the compressor and the injection valve at the expansion valve.

Function sequence, high-pressure side
The refrigerant compressor driven by the engine draws in the cold gaseous refrigerant from the evaporator, compresses it, whereby it is heated and delivers it to the condenser. The compressed hot refrigerant is cooled in the condenser by the outside air flowing past. On reaching the dew point dependent on the pressure, the refrigerant condenses and changes in terms of its physical state from gaseous to fluid.
The completely liquefied refrigerant then flows into the fluid reservoir (drier). While it is flowing through the fluid reservoir, moisture is removed from the refrigerant and it is cleansed of any chemical and mechanical impurities in order to protect the subsequent components. The cleansed refrigerant flows on to the expansion valve and to the rear air conditioning refrigerant shutoff valve. There the liquid refrigerant, which is highly pressurized, is injected into the corresponding evaporator.

Function sequence, low-pressure side
The liquid refrigerant decompresses in the corresponding evaporator and changes again in terms of its physical state from fluid to gaseous. The evaporation heat required for the evaporation is removed from the air flowing past at the evaporator fins, cooling it down in the process. The refrigerant, which is completely gaseous once more, is drawn in again and compressed by the refrigerant compressor.

The cooled air is supplied to the vehicle interior via the blower motor (A32m1) and the rear blower motor (M2/1) (with code (582) Rear air conditioning).

To prevent the particular evaporator from icing up, the refrigerant compressor or the rear air conditioning refrigerant shutoff valve is shut off by the AAC [KLA] control unit if the temperature drops below a specific value at the evaporator.

The temperature at the evaporator and at the rear air conditioning evaporator is measured by the evaporator temperature sensor and the rear air conditioning evaporator temperature sensor.