Refrigerant circuit function

P83.40-4908-78

Function requirements, general

 Engine running

 Climate control switched on

Refrigerant circuit in general

The refrigerant circuit is regulated by the climate control control unit (N22/1).

 Detailed information on the climate control regulation function is available in the "Climate control regulation, function" subfunction.

The refrigeration circuit basically consists of the following components:

 Refrigerant compressor

 Condenser

 Accumulator (drier)

 Expansion valve

 Evaporator

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

The refrigerant circuit consists of the following functional components:

 High-pressure side

 Low-pressure side

The separation points for this are the valve plates on the refrigerant compressor and the injection valve on the expansion valve.

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 blow-by air or the outside air sucked in by the fan motor (M4/7).

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 refrigerant then flows into the accumulator (drier). While it is flowing through the fluid reservoir, moisture is removed from the refrigerant, vapor locks are separated and any mechanical impurities are filtered out in order to protect the downstream components from these. The cleaned refrigerant then flows to the expansion valve. The liquid refrigerant, which is under high pressure, is injected into the evaporator.

Low-pressure side

The liquid refrigerant decompresses in the 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 blow-by air 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 led to the vehicle interior via the blower motor (A32m1).

 To prevent the evaporator from icing up, the A/C compressor is switched off by the climate control control unit when a specific evaporator temperature is dropped below. The temperature at the evaporator is recorded by the evaporator temperature sensor (B10/6).