Refrigerant circuit function - GF83.40-P-2001RF
Model 205, 253
Model 205 (except 205.012/047/147/212/247), 253
Model 205.012/212
Model 205.047/147/247
Function requirements, general
- Engine running (except model 205.012/047/147/212/247)
- Electric refrigerant compressor switched on (model 205.012/047/147/212/247)
- Climate control switched on
Refrigerant circuit in general
The refrigerant circuit is regulated by the climate control unit (N22/1).
The refrigeration circuit basically consists of the following components:
- Refrigerant compressor (except model 205.012/047/147/212/247)
- Electric A/C compressor (model 205.012/047/147/212/247)
- Condenser
- Accumulator (drier)
- Expansion valve (except model 205.012/047/147/212/247)
- Evaporator
- Inner heat exchanger
- Heat exchanger (model 205.047/147/247)
- Front evaporator shutoff valve (model 205.012/047/147/212/247)
- High-voltage battery cooling system shutoff valve (model 205.012/212)
- High-voltage battery cooling system expansion valve (model 205.047/147/247)
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 at the respective refrigerant compressor and the injection valve at the expansion valve.
High-pressure side
The respective refrigerant compressor draws in the cold, gaseous refrigerant from the evaporator and 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 cleansed refrigerant flows on to the expansion valve (except model 205.012/047/147/212/247), to the front evaporator shutoff valve (model 205.012/047/147/212/247) or to the high-voltage battery cooling system shutoff valve (model 205.012/212) or to the high-voltage battery cooling expansion valve (model 205.047/147/247). The liquid refrigerant which is under high pressure is injected into the respective evaporator there.
Model 205.012/212
Through actuation of the high-voltage battery cooling shutoff valve the refrigerant flows through the evaporator integrated into the high-voltage battery module. This serves to remove heat from the high-voltage battery.
Model 205.047/147/247
Through actuation of the expansion valve for the high-voltage battery cooling system, the refrigerant circuit is extended to include the cooling circuit for the high-voltage battery. This means that the high-voltage battery can be cooled by refrigerant. If the high-voltage battery is cooled, the cleaned refrigerant flows through the heat exchanger and cools the high-voltage battery cooling system's coolant flowing through the heat exchanger.
Low-pressure side
The liquid refrigerant decompresses in the respective 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 respective refrigerant compressor. The cooled air is led to the vehicle interior via the blower motor (A32m1).
Model 205.047/147/247
If the high-voltage battery is cooled, the refrigerant changes its aggregation state from liquid to gaseous when flowing through the high-voltage battery cooling expansion valve. The gaseous refrigerant is then sucked in by the A/C compressor and compressed again.
To prevent the evaporator from icing up, when a specific temperature is undershot on model 205 (except 205.012/047/147/212/247), 253, the refrigerant compressor is switched off by the climate control unit. On model 205.012/047/147/212/247, the climate control unit actuates the shutoff valves accordingly. This enables the electrical A/C compressor to continue to be operated. This is necessary, to ensure that the high-voltage battery can also be operated even at outside temperatures of T < 10 °C.
| Overview of system components for climate control | GF83.40-P-9994RF |