In the cooling mode, cool vapour (green in the graphic) arrives at the compressor after absorbing heat from the air in the building. The compressor compresses the cool vapour into a smaller volume, increasing its heat density.

The refrigerant exits the compressor as a hot vapour (red in the graphic) which then goes into the earth loop field. The loops act as a condenser condensing the vapour until it is virtually all liquid. The refrigerant leaves the earth loops as a warm liquid (yellow in the graphic).

The flow control regulates the flow from the condenser such that only liquid refrigerant passes through the control. The refrigerant expands as it exits the flow control unit and becomes a cold liquid (blue in the graphic). Because the liquid evaporates as it passes through the cooling coil located in the air handler, it absorbs heat from the air blowing over the coil surface and thus cools your home.