How your Air Conditioner Works

First, let’s understand what an air conditioning system really does in a very basic way.  Air conditioning is simply a means of taking heat from one place and putting it somewhere else. In effect it makes you cool and comfortable, but it cools things off because it is removing heat. In the basics of thermodynamics, heat exists all the way to absolute zero, where all thermal motion ceases to exist.  Absolute zero refers to a temperature of -459.67 degrees Fahrenheit.

A typical residential air conditioning system consists of a few key components.  The part outside your home is called a condensing unit.  The part inside your home is called an air handler.  The condensing unit consists of a compressor (used to move the refrigerant around the system), a condenser coil and a condenser fan. The air handler consists of an evaporator coil and a blower.  These two sections are connected by copper piping.  A thermostat controls the function of these components.

When the thermostat senses a rise in temperature above the set point, the system turns on.  Liquid refrigerant (Freon / Puron) is pumped into the air handler component called the evaporator coil.  It is sprayed into this coil much like an aerosol can sprays.  These liquid droplets change states from a liquid to a gas and in that process absorb the heat being introduced to the coil by the air movement across it from the indoor blower.  This change of state of the refrigerant from a liquid to a gas is the essence of how the heat is absorbed.

The opposite thing happens on the outside of the home.  The refrigerant returns to the condensing unit in the form of a gas.  There it is compressed by the compressor and cycles through the condenser coil where the heat that was absorbed in the evaporation process is discharged.  As this refrigerant releases this heat, the refrigerant condenses back into a liquid from its gaseous, heat laden state.  The refrigerant then goes back to the evaporator to start the whole process over again.