Evaporator Core: Description and Operation

Design
The design of the evaporator depends on whether the car is equipped with a four-cylinder or V6 engine and whether it is left-hand drive or right-hand drive.
1 LHD 4-cylinder. The expansion valve is situated in the engine bay. The evaporator's pipes must be cut off before the evaporator is taken out of the climate control unit.
2 LHD V6. The expansion valve is situated in the climate control unit.
3 RHD. The expansion valve is situated in the engine bay.
4 As a spare for LHD cars we supply the evaporator in a V6 design with a block so that the pipes can be joined to the lead-through in the bulkhead partition.
5 In cars with RHD the spare evaporator is supplied with the same block in RHD design.

Technical Description
The incoming refrigerant expands and boils (evaporates) in the evaporator and thus takes up heat from the ambient air. When heat is taken up, water condenses on the outside of the evaporator. This condensate is drained to the engine bay via a hose.

Mounted on the evaporator is an anti-freeze thermostat which prevents freezing and the formation of ice on the evaporator. A sensor is in contact with the evaporator's low-pressure pipe. When the temperature drops below +2 °C the compressor's power supply is turned off. When the temperature rises above +5 °C the thermostat closes again and the compressor is once more supplied with power.

Mode Of Operation
After the expansion valve, the refrigerant enters the evaporator where it expands. The pressure in the evaporator is considerably lower due to the suction action in the compressor. When the refrigerant expands, it becomes a gas (evaporates). Heat must be added to make this happen. This heat is taken from the air around the evaporator. The cooled air is then sent to the interior of the car. The refrigerant then goes to the compressor in the form of a gas.