Compressor
The compressor takes in cooled vapour and compresses it - the compression causes the gas to increase in temperature and pressure.

Condensor and Cooling Fan
The hot gas enters the condensor and is cooled by ambient air being forced over the condensor, this causes the hot gas to change its state to a liquid.

Liquid Line
The liquid line carries the cooled liquid refrigerant to the expansion valve.

Expansion Valve and Evaporator
The expansion valve allows the liquid refrigerant to expand into the evaporator, which causes heat from the surrounding area to be absorbed changing the refrigerants state back into a low pressure vapour.

Cold Vapour Line
The cold vapour line returns the refrigerant vapour to the comperssor, at which point the cooling process is repeated.