Heater
The engine coolant is the working fluid of the car interior heater. Coolant is supplied under pressure to the heater core through the inlet hose.
The heater core is located inside the air conditioning unit. The heat from the coolant flowing through the heater core is transferred to the air flowing through the air conditioning unit. Heated air is supplied to the passenger compartment, providing a comfortable temperature.
The amount of warm air supplied to the passenger compartment is controlled by opening or closing the temperature damper of the air conditioner.
The coolant leaves the heater core through the return hose and returns to the cooling system again.
Air conditioner
The working fluid of an air conditioning system is a refrigerant. Currently, only R-134a refrigerant is approved for use in automotive air conditioning systems, a low-temperature gas capable of transferring excess heat and moisture from the passenger compartment to the atmospheric air.
The air conditioning compressor is driven by the crankshaft through a belt drive and is activated when the electromagnetic clutch is activated. The compressor pressurizes the vaporized refrigerant, and when compressed, the refrigerant heats up. The refrigerant leaves the compressor and enters the condenser under pressure through a hose. The air conditioning system is mechanically protected from overpressure by a bypass valve. If the pressure sensor fails or the system becomes clogged and the pressure builds up, the bypass valve opens and releases the pressure.
The compressed refrigerant vapor enters the condenser at high pressure and high temperature. Flowing through the condenser, the refrigerant gives off heat to the environment. Cooling causes the refrigerant to condense and change from a gaseous to a liquid state.
The condenser is located in front of the radiator for maximum heat transfer. The condenser is made of aluminum and has fins for fast heat dissipation. The semi-cooled liquid refrigerant leaves the condenser and enters the expansion valve via the liquid line.
The expansion valve is located between the condenser and evaporator. It is the dividing point between the high and low pressure circuits of the air conditioning system. In the expansion valve, the pressure of the refrigerant drops and it passes from a liquid to a gaseous state, while its temperature drops sharply. The expansion valve also measures the amount of liquid refrigerant that then enters the evaporator.
The low pressure refrigerant from the expansion valve enters the evaporator core. Atmospheric air passing through the air conditioning unit is cooled and dried by the evaporator, since moisture from it settles in the form of condensate on the evaporator plates and is then removed from the car, flowing down through special channels. The refrigerant in the evaporator heats up, after which it again enters the compressor through the intake line in a vapor state, completing the heat exchange cycle. In the compressor, the refrigerant is compressed again and the cycle repeats.
Conditioned air is distributed through the air conditioning unit throughout the vehicle interior, providing the required air temperature.
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