Refrigerant Circuit, Function - GF83.40-P-2008KJ
MODEL 453.0 (except 453.091), 453.3 (except 453.391), 453.4 (except 453.491) with CODE I01 (Automatic air conditioning)
MODEL 453.0 (except 453.091), 453.3 (except 453.391), 453.4 (except 453.491) with CODE I77 (Air conditioning, manual)
Function requirements, general
- Engine running
- Automatic air conditioning switched on (with code (I01) Automatic air conditioning)
- Air conditioning system switched on manually (with code (I01) Manual air conditioning system)
Refrigerant circuit in genera)
The refrigerant circuit is controlled by the climate control and operating unit (N23) (with code (I77) Manual air conditioning system) or the air conditioning system operating unit (N20) (with code (I01) Automatic air conditioning).
Detailed information on the climate control regulation function is available in the function description "Climate control regulation, function". 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 is made up as follows:
- High-pressure side
- Low-pressure side
The separation points are the valve plate on the A/C 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 passing flow of air or the outside air drawn in by the fan (M4/4). On reaching the pressure-specific dew point temperature, 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 its physical state from liquid to gaseous. The evaporation heat required for the evaporation is removed from the blowby air at the evaporator fins, cooling it down in the process. The refrigerant, which is completely gaseous once more, is drawn in and compressed by the refrigerant compressor.
The cooled air is led to the interior of the vehicle by actuating the blower motor (M2).
To prevent the evaporator from icing up, the refrigerant compressor is switched off by the ME-SFI [ME] control unit (N3/10) if the evaporator temperature drops below a certain level.
The temperature at the evaporator is recorded by the evaporator temperature sensor. The signals of the evaporator temperature sensor are read in directly by the climate control and operating unit (with code (I77) Manual air conditioning system) or the climate control unit (with code (I01) Automatic air conditioning).
| Overview of system components for climate control | GF83.40-P-9994KJ |