GF83.40-P-2005LEH Automatic Air Conditioning Refrigerant Circuit, Function
GF83.40-P-2005LEH Automatic Air Conditioning Refrigerant Circuit, Function
Component Identification:
General function requirements
^ Circuit 61
^ Automatic air conditioning switched on
^ Electric refrigerant compressor switched on
Circuit 61 is required to start the electric refrigerant compressor. Then cooling is possible even without engine speed (stop mode).
The status of circuit 61 is provided by the ME-SFI [ME] control unit (N3/10) via chassis CAN (CAN E) and forwarded from central gateway control unit (N93) via interior CAN (CAN B) to 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) (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:
- Electric refrigerant compressor
- Condenser
- Fluid reservoir
- Expansion valve
- Evaporator
- Hoses and pipelines
An evaporator is also integrated into the high-voltage battery module.
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 electric refrigerant compressor draws in the cold gaseous refrigerant from the corresponding 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 cleaned refrigerant flows back to the expansion valve, the rear air conditioning refrigerant shutoff valve and the high-voltage battery cooling system 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. Thermal energy is also extracted from the high-voltage battery (A100g1). This is integrated into the high- voltage battery module.
The refrigerant, which is completely gaseous once more, is drawn in again and compressed by the electric 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).
The cooled coolant is used to cool the high-voltage battery. The coolant continues its course to the condenser and from there to the electric refrigerant compressor. This is necessary to prevent damage to the electric refrigerant compressor by means of liquid refrigerant.
To prevent the particular evaporator from icing up, the electric 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.
The battery management system control unit (N82/2) controls the battery temperature via the high-voltage battery cooling system shutoff valve.
