Air conditioners use refrigerants that easily convert from a gas to a liquid and back again. These compounds serve as a vector to transfer heat from the air in your home to the outside air.
There are three main parts to an air conditioner unit; a compressor, a condenser and an evaporator.
The air in your home moves over the cold evaporator coil that’s inside the house allowing the heat from the air to be absorbed within the refrigerant (a heat transfer fluid).
The refrigerant then flows to the warm condenser coil located outside your home. The compressor then compresses that refrigerant making it really hot, much hotter than the air outside. The outside air will absorb the heat in the refrigerant flowing through the outdoor coil until it cools down and flows back into your home, where it can absorb more heat. This cycle will continue until your home reaches the temperature set by your thermostat.
Your air conditioner also has to move the air. This is done with a fan which circulates the air from your home through a vent and blows it over the cooled evaporator coil and then blows the cool air through your air ducts to cool your home.