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

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

Component Identification:

Function requirements, general
^ Circuit 61 ON
^ Automatic air conditioning switched on
^ Refrigerant pressure and refrigerant temperature OK
^ Refrigerant compressor runs error free

The circuit status of circuit 61 is provided by the CDI control unit (N3/9) (with diesel engine) or ME-SFI [ME] control unit (N3/10) (with gasoline engine) to the chassis CAN (CAN E) and routed by the front SAM control unit with fuse and relay module (N10/1) to the 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:
- Refrigerant compressor
- Condenser
- Accumulator (drier)
- 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:
^ Function sequence for high-pressure side
^ Function sequence for low-pressure side

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

Function sequence for 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 in the condenser is cooled by the outside air flowing past or by the outside air drawn in by the combustion engine and air conditioning with integrated control 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 accumulator, moisture is removed from the refrigerant, vapor lock is separated and the refrigerant is cleansed of any 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.

Function sequence for 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).

As of 1.12.09 a coaxial heat exchanger will be installed. In the process, the output and efficiency of the refrigerant circuit are increased.

To prevent the evaporator from icing up, the refrigerant compressor is switched off by the control and operating unit if the temperature drops below a specific value at the evaporator. The evaporator temperature is recorded by the evaporator temperature sensor.