How Car Air Conditioning works:
Motor vehicle air conditioning follows the normal cycle of refrigeration which utilises the following processes: Compression, Condensation and Evaporation
Refrigerant is pumped around the air conditioning system, which is split into 2 parts: the high pressure side (top, red) and the low pressure side (bottom, blue). The refrigerant vapour is drawn from the low pressure side to the high pressure side by the compressor (A). In this process the vapour is heated to a temperature of between 25-75 degrees centigrade.
The hot vapour is then pumped to the condenser (B) which consists of a series of pipes surrounded by a cooling core. The refrigerant vapour is cooled by the air stream, with the assistance of the condenser fan (or radiator fan) so that it condenses into a liquid.
The liquid refrigerant then flows into the receiver drier which stores and filters the refrigerant until required by the evaporator (C).
The suction effect of the compressor (A) on the low pressure side of the circuit “sucks” the liquid refrigerant through the “controlled restriction”. This causes an abrupt drop in refrigerant pressure as it passes through the “controlled restriction”, which causes the liquid to evaporate. During the evaporation process heat is extracted from the air passing across the evaporator coil (C). This cooled air is then blown into the vehicle.