An Air Handler (The Indoor Section):
The air handler consists of two parts, a blower and an evaporator coil. Depending on whether the air handler is in conjunction with a furnace or exists as an independent unit, the set up will be slightly different. If the air handler is part of a furnace system, the blower will be housed within the furnace case and serve the dual function of circulating the air for both heat and cooling modes. The evaporator coil will then be adjacent or on top of the furnace. If the air handler is an independent unit, the blower and evaporator coil will be housed together in a single case.
The blower serves the function of pulling air from the return ductwork and blowing it across the evaporator coil. Within the evaporator coil, compressed refigerant begins to expand and in the process of expansion to a gas, draws heat from the surrounding air. The cooled air then flows out into the supply ductwork where it is distributed throughout the house.
The gaseous refrigerant is transferred to the condensing unit through the lineset.
The Lineset consists of two pipes connecting the indoor and outdoor units, one carrying refrigerant in a gaseous form, the other, in a liquid.
A Condensor Unit (The Outdoor Section):
The condensing unit contains a coil, a fan, and a compressor.
The gaseous refrigerant first runs through the coil where the fan pulls air across the coils to help dissipate the heat from the refrigerant. The compressor then takes the cooled refrigerant and compresses it back into a liquid before it passes out of the condensor and into the lineset to head back towards the evaporator coil.
An expansion valve:
Before reaching the evaporator coil, an expansion valve regulates the pressure of the refrigerant and whether or not the refrigerant continues on through the system again.
The supply and return dectwork serve to pipe the cooled air throughout the home and take the warmer air into the air conditioning unit.
The thermostat acts a control, monitoring the temperature of the house, and determining in which mode the system should be functioning.