How an Air Conditioner Uses a Heat Exchanger

In the air conditioner, the refrigerant channels through the various components, moving heat as it goes.
The refrigerant starts out as a low-pressure liquid in the evaporator coils.
A fan blows the warm air in an indoor space across the coils, and the refrigerant changes into a vapor as it absorbs the heat from the air and, in turn, cools the room.
A low-pressure warm gas now, the refrigerant travels into the compressor-usually located outdoors-where it converts into a high-pressure, hot gas.
The refrigerant moves into the condenser, also typically outside.
As air flows over the condenser, it carries away heat from the refrigerant with it, causing the refrigerant to change again into a high-pressure, cool liquid.
The refrigerant will cool off even more in the expansion valve before returning to the evaporator to absorb more heat to carry out of the building.