How Does an AC Cool My Home?

Published on: June 23, 2014
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Humans have been finding creative ways to keep cool for thousands of years, and in modern times, the preferred method is air conditioning. Since the first modern air conditioners hit production over a century ago, the HVAC industry has made great strides in terms of energy efficiency, cooling power and general air conditioning performance. However, the basic process at the core of every air conditioner has remained more or less unchanged since Willis Carrier’s breakthrough in 1902.

The Cooling Cycle

To understand how an air conditioner works, you need to understand some of the basic physical properties of matter. When liquids evaporate and become gaseous, they absorb heat from the surrounding air. Conversely, when a gas condenses to become a liquid, heat is released into the surrounding air. The gas essentially stores heat, which can then easily be transported from place to place.

Air conditioners use special chemicals called refrigerants, which can exist in both liquid and gaseous states at temperatures relatively close to room temperature. At the evaporator coil, liquid refrigerant chemicals absorb heat and become gaseous. The air conditioner then transports the refrigerant vapor to the condenser coil. There, a special pump called a compressor forces the refrigerant to become liquid again, releasing that heat. A fan blows the hot air away from the house while the liquid refrigerant returns to the evaporator to repeat the cycle.

In a standard air conditioner, the evaporator coil is located inside the house and the condenser sits in the outdoor unit. That means the cycle effectively carries heat from the indoor air to the outdoor air, lowering the inside temperature. Heat pumps use the same cycle, but they can run it in either direction, pumping heat out of or into the home as needed.

More About Refrigerant

Once Carrier invented air conditioning, the search was on for a non-toxic refrigerant chemical that would work well in residential air conditioners. A few decades later, that search culminated with the discovery of Freon, a family of chemicals that can serve well as refrigerants but are harmless to humans. For decades, the HVAC industry used R-22 refrigerant, but concerns about environmental effects led to a recent switch to R-434A, sold under the brand name Puron. Because R-22 is being phased out, older air conditioners that still use it can be more expensive to maintain.

A key feature of the cooling cycle is that, while refrigerant chemicals are used extensively throughout the process, they aren’t actually used up during normal operation. No refrigerant is lost during the phase change from liquid to gas and back to liquid. Thus, if your air conditioner’s refrigerant gauge is below the recommended range, there is almost certainly a refrigerant leak. You’ll need to call an HVAC contractor right away to repair the refrigerant lines.

Now that you know how air conditioners cool your home, it’s time to take stock of your climate control needs. You depend on that cooling cycle throughout the season, and you ought to be able to depend on the technicians who repair and maintain your air conditioner. Whether you need AC replacement, emergency repairs or just general maintenance, our online tools will help you connect with a local HVAC company that can take care of your family’s cooling needs.