Ducted reverse cycle air conditioning consists of an outside unit called a compressor and an inside unit placed within the roof. This internal unit is connected to a series of outlets within the house via ductwork. Depending on the climate function chosen warmed or cooled air is pumped to all rooms that have an outlet.
All refrigerated air conditioning systems, including reverse cycle air conditioners, are heat pumps (so are refrigerators). A 'heat pump' transfers heat from one zone to another. Heat pumps consist of an indoor and outdoor coil connected by a pipe through which a refrigerant circulates (note that refrigerants used are now CFC free).
As warm air passes over the inside coil, heat from the air is absorbed by the refrigerant. This cools the air that is released back into the room. Meanwhile, the heat absorbed by the refrigerant is transferred to the external coil where it is released to the outside air.