Taken literally, air conditioning includes the cooling and heating of air, cleaning it and controlling its moisture level: conditioning it to provide maximum indoor comfort

An air conditioner transfers heat from the inside of a building, where it is not wanted, to the outside. Refrigerant in the system absorbs the excess heat and is pumped through a closed system of piping to an outside coil. A fan blows outside air over the hot coil, transferring heat from the refrigerant to the outdoor air. Because the heat is removed from the indoor air, the indoor area is cooled.

An air conditioning system generally consists of five mechanical components:

1. A compressor
2. A fan
3. A condenser coil (hot)
4. An evaporator coil (cool)
5. A chemical refrigerant

Most central air conditioning systems include of a "hot" side, outside your home, and a "cold" side, inside your home. The "hot" side generally consists of a condensing coil, a compressor and a fan.

The "cold" side is usually located within your furnace. The furnace blows air through an evaporator coil, which cools the air, and routes this cool air throughout your home using a series of air ducts.

The cleaning function of air conditioners is performed by filters, which remove dust from the air.