1 Indoor unit:
A fan blows the hot indoor air over a heat exchanging coil through which cold refrigerant flows. The cold refrigerant absorbs the heat from the air and cooled air is blown into the room.
2 Copper piping:
The refrigerant circulates through the units and the piping and take the heat from the indoor unit to the outdoor unit.
3 Outdoor unit:
Through compression, the refrigerant gas is heated and its boiling point increases. In the outdoor unit the obtained heat thought compression is released to the outdoor air by means of a fan which blows the outdoor air over a heat exchanging coil.
The liquid refrigerant flows back to the indoor unit.
5 Indoor unit
Back in the indoor unit, the refrigerant is decompressed and thus enabled to extract heat form the indoor air.