How Does Air Conditioning Work?

Air conditioning was created in 1902. Though it took a number of years to really get popular, it started being used in theaters and department stores to keep the buildings cool and comfortable in the summer months. Customers would then go to these places to beat the heat and stay cool. Eventually, air conditioners were created for home use, too, and most homes in areas where the heat can be unbearable during the summer will have an air conditioner to keep the home cool. But how does air conditioning work? It’s actually a relatively simple process. 

What Happens Indoors

To cool the air, the heat from the inside of the home needs to be removed, and the air needs to be replaced with cooler air. Inside the home, the AC unit blows cool air across a coil that’s filled with refrigerant. The heat is absorbed by the refrigerant, changing it from a liquid to a gas and allowing cool air to flow back into the home. This is what cools down the air in the home, but it only works for so long because the refrigerant can’t pull more heat from the air if it’s already a gas. The heat needs to be moved outside so the refrigerant can liquify again and pull more heat from the air. 

What Happens Outdoors

Outside of the home is where the heat dissipates. The compressor puts pressure on the refrigerant to turn it back into a liquid, dispersing the heat to the outside of the home. A fan is used to pull the air from outside of the unit through the unit to absorb the heat, allowing the refrigerant to become a liquid again before it goes back inside the house. These two steps, outside and inside, work together to keep the refrigerant circulating and remove as much heat as possible from the air inside the home until it reaches the desired temperature. At that point, the system turns off until it’s needed again.  

Setting the Temperature

Thermostats tell the air conditioner when to start working and when to stop. Without them, the air conditioning system would need to be turned on and off manually or left to run, which could make the home too cool and will wear out the system a lot faster. The thermostat checks the temperature inside the home, turning the air conditioner on when the air gets too hot. It then monitors the temperature while the home cools and turns off the system when the home’s air is cool enough. It will do this automatically, turning the system on and off as needed, to keep the home at the desired temperature. 

Ductless Air Conditioning

With a standard air conditioning system, ducts are used to move the cool air throughout the home. With a ductless system, however, the unit is in the room that needs to be cooled, so there is no need for ducts. There will be air conditioning units inside each of the rooms that may need to be cooled, so they can be cooled to different temperatures or to turn off air conditioning in rooms that aren’t needed. Homeowners may prefer these to prevent some of the issues that occur with ducted air conditioners or to have more control over the temperatures inside their homes. 


In areas with high humidity, a humidistat may be used. This is basically a thermostat that’s designed to detect humidity instead of temperature and can turn the air conditioner on or off as needed to control the humidity in the home. If there is low humidity, the humidistat will turn off the air conditioning to save energy. If there is a lot of humidity in the air, it can turn on the air conditioner to cool the home and remove the humidity. This is done to help prevent issues like mold in areas where the humidity can be incredibly high. 

When Something Goes Wrong, Call Air Care!

Though the basic premise for how air conditioning works is relatively simple, the systems can be incredibly complex. There are a ton of moving parts that all need to work together to keep the home cooled without wasting energy. Problems homeowners may experience include the system running too long, the system using shorter cycles to cool the home, or the system failing to turn on at all. When any of these issues occur, homeowners should call a local HVAC professional as soon as possible. Even though the homeowner may understand how the system works, it takes experience and training to be able to determine what’s not working and how to fix it properly. 

Air conditioning has been around for many years, and it still works on the same basic principles it did in the beginning. There have been changes to help the system run more efficiently or make them more environmentally friendly, and they have become more complex over time. If there is anything not working right on your air conditioner, contact Air Care Heating and Cooling now for help.