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

GF83.40-P-2005FQ Automatic Air Conditioning Refrigerant Circuit, Function
MODEL 218





1 Condenser
2 Fluid reservoir
3 Expansion valve
4 Evaporator
A9 AC compressor
B10/6 Evaporator temperature sensor
B12 Refrigerant pressure sensor
A High pressure, gaseous
B High pressure, liquid
C Low pressure, liquid
D Low pressure, gaseous

Function requirements, general
^ Engine running
^ Refrigerant compressor SWITCHED ON
The "Engine running" signal is sent by the CDI control unit (N3/9) (with diesel engine) or by the ME-SFI [ME] control unit (N3/10) (with gasoline engine) to the chassis CAN (CAN E) and sent by the front SAM control unit with fuse and relay module (N10/1) via interior CAN (CAN B).

Automatic air conditioning refrigerant circuit, general
Control of the automatic air conditioning refrigerant circuit is performed by the automatic air conditioning control and operating unit (N22/7). The air in the vehicle interior is cooled depending on the setting on the control and operating unit or rear automatic air conditioning control unit (N22/4) (with code (581) comfort automatic air conditioning ) by the automatic air conditioning refrigerant circuit.
The automatic air conditioning refrigerant circuit mainly consists of the following components:
- AC 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 function consists of the following functional components:
^ High pressure side
^ Low pressure side
The separation points for this are the valve plates at the refrigerant compressor and the injection valve at 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 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 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 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 led to the vehicle interior via the blower motor (A32m1).
To prevent the evaporator from icing up, if the temperature drops below a specific value at the evaporator, the refrigerant compressor is switched off by the control and operating unit.
The evaporator temperature is recorded by the evaporator temperature sensor.