In 1902, Willis Carrier invented the first modern air-conditioning system. Carrier invention has contributed to the emergence of many industries that keep fuelling our economy today. In the beginning years, air conditioning contributed to boosting the manufacture of everything from baked goods to war supplies. It brought direct access to summer blockbuster movies, as people rushed to cool movie theatres to escape the heat. Precise control of temperature and humidity has even allowed the development of indoor shopping malls, transatlantic flights and computers and servers that power the Internet. Today’s “modern” cooling systems still function according to the same fundamental principles, providing fresh and pleasant air to the people inside. 

Air conditioners are of many different shapes and sizes, but they all operate on the same fundamental principle. An air conditioner generates cold air inside your home or an indoor space by removing heat and moisture from the indoor air. It blows the cooled air back into the indoor space and transfers undesirable heat and moisture to the outside. A standard air conditioner or cooling system uses a specialized chemical called a refrigerant and has three main operating components: a compressor, a condensing coil and an evaporating coil. They work together to quickly transform refrigerant from gas to liquid and vice versa. The compressor boosts the pressure and temperature of the refrigerant gas and sends it to the condenser coil where it is turned into a liquid. Then the refrigerant returns inside and enters the evaporator coil. There, the liquid refrigerant evaporates and cools the indoor coil. A fan blows the indoor air over the cold evaporator coil where the heat from the house is removed by the refrigerant. The cooled air then circulates through the entire house while the heated evaporated gas is returned outside to the compressor. The heat is then released to the outside air when the refrigerant returns to a liquid state. This process continues until your home has reached the intended temperature.


Many residences in North America have dual system air conditioners, often referred to as “central air.” Air conditioning systems include a number of components and do more than just cool the air indoors. They can also regulate humidity, air quality and airflow in your home. Now that you have a general understanding of how air conditioners work, let’s take a closer look and explain the whole process.

The thermostat, which is generally mounted on a wall in a central location in the house, monitors and regulates the temperature of the indoor air. The cooling process begins when the thermostat detects that the air temperature requires lowering and sends signals to the air conditioning system controls inside and outside the house to turn on. The indoor unit’s fan removes warm air from inside the house through return air ducts. This air passes over filters where dust, lint and other airborne particles are trapped. The warm filtered indoor air is then passed through the cold evaporation coil. When the liquid refrigerant inside the evaporation coil turns into gas, the heat from the indoor air is being absorbed by the refrigerant, which cools the air as it passes through the coil. The fan blowing from the indoor unit will then pump the cooled air to different rooms in the house using ducts.