P83.40-4774-78
Shown except CODE 582 (Rear air conditioning) |
1 | Condenser | C | Low pressure, liquid | |
2 | Accumulator (drier) | D | Low pressure, gaseous | |
3 | Expansion valve | A9 | A/C compressor (except CODE B09 (A/C compressor with magnetic clutch)) | |
4 | Evaporator | A9/7 | A/C compressor with magnetic clutch (with CODE B09 (A/C compressor with magnetic clutch)) | |
5 | Inner heat exchanger | B10/6 | Evaporator temperature sensor | |
A | High pressure, gaseous | B12 | Refrigerant pressure sensor | |
B | High pressure, liquid |
P83.40-4775-79
Shown with CODE 582 (Rear air conditioning) |
1 | Condenser | C | Low pressure, liquid | |
2 | Accumulator (drier) | D | Low pressure, gaseous | |
3 | Expansion valve | A9 | A/C compressor (except CODE B09 (A/C compressor with magnetic clutch)) | |
4 | Evaporator | A9/7 | A/C compressor with magnetic clutch (with CODE B09 (A/C compressor with magnetic clutch)) | |
5 | Inner heat exchanger | B10/6 | Evaporator temperature sensor | |
6 | Rear air conditioning evaporator (with CODE 582 (Rear air conditioning)) | B10/11 | Rear air conditioning evaporator temperature sensor (with CODE 582 (Rear A/C system)) | |
A | High pressure, gaseous | B12 | Refrigerant pressure sensor | |
B | High pressure, liquid | Y19/9 | Rear air conditioning evaporator shutoff valve (with CODE 582 (Rear air conditioning)) |
Function requirements, general
Engine running
Automatic air conditioning switched on
Refrigerant circuit in general
The refrigerant circuit is controlled by the automatic air conditioning control and operating unit (N22/7).
The refrigeration circuit basically consists of the following components:
Refrigerant compressor
Condenser
Accumulator (drier)
Expansion valve
Evaporator
Inner heat exchanger
Shutoff valve (with CODE 582 (Rear air conditioning))
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 plate 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 blowby 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 cleaned refrigerant flows on to the expansion valve and to the rear air conditioning system evaporator shutoff valve (with CODE 582 (Rear air conditioning)). The liquid refrigerant which is under high pressure is injected into the respective evaporator there.
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 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).
On vehicles with CODE 581 (Comfort automatic air conditioning), the rear area also has cool air routed to it through the rear blower motor (M2/1).
On vehicles with CODE 582 (Rear air conditioning), the rear air conditioning blower motor (M2/29) also routes air through the rear air conditioning system evaporator.
To prevent the respective evaporator from icing up, the refrigerant compressor is switched off by the automatic climate control control and operating unit if the temperature drops below a specific value at the evaporator.
The temperature at the evaporator is measured by the evaporator temperature sensor and the rear air conditioning evaporator temperature sensor.
The inner heat exchanger is installed to increase the cooling output of the refrigerant circuit. A coaxial line further cools the liquid refrigerant coming from the condenser using the cold suction gas coming from the evaporator.
Referenced documents
- gf8340p9995gr Overview of automatic climate control system components