How Does Central Air Conditioning Work?

Most homes have central air conditioning systems that help to keep the indoor environments cool during the summer months. While many people understand how to set their thermostats, not many know what happens after their AC units kick on. It’s highly advisable to have a general understanding of how your air conditioning system works so that you can remedy small issues and perform necessary preventative maintenance on your equipment.

Your Thermostat Starts Your Air Conditioner

The thermostat on your wall is what starts the entire air conditioning process. When the ambient temperature inside of your house goes above the set temperature on your thermostat, your thermostat signals to the remaining AC unit components that it’s time to turn on.

The warm air inside of your home is pulled into the return vents via an indoor blower fan that’s inside of your air conditioning system. The air will pass through your air filter and air purifier if you have one in your AC unit. This helps to clean the air by removing unwanted pollutants like pollen and dust from the air.

Depending on your desired indoor air quality, you have several options for purchasing air filters. The most popular are pleated and HEPA air filters. If you have young children or severe allergies, you should consider upgrading to the HEPA filter. It will be more expensive, but it will remove more allergens from the air inside of your residence. The more allergens that your filter removes, the less likely your allergies are to flare up.



Those who have existing respiratory diseases like COPD should highly consider having an air purifier installed in their houses. An air purifier gives you additional filtering capabilities that a simple air filter can’t. For example, there are electric air purifiers and photocatalytic air filters.

The Magic Of Refrigerant

Once the hot indoor air is filtered, it passes over the evaporator coil. This coil is filled with a liquid substance called refrigerant. As the heat in the air goes over the coil, it’s transferred to the refrigerant. This turns the refrigerant from a liquid state to a gas state.

During this heat transfer process, some of the humidity inside of the air is removed. This water drips off the evaporator coil and falls into the drain pan, where it drains out of your home. The now cooled air, due to the heat transfer process, is returned to the rooms in your house via the supply venting.

As you’ve learned, the air conditioning process is more accurately described as a heat transfer process. The heat and humidity are removed from the air, and that makes it feel much cooler to the body. Removing humidity is also an important part of the air conditioning process.

When humidity levels are high, your body will feel much warmer than it actually is. This is due to the fact that the sweat the body produces to cool itself won’t evaporate fully. This leaves you feeling clammy and sweaty. In fact, high humidity’s effect on your body can make you feel as if it’s between two and eight degrees warmer than it actually is.

The Outdoor Processes

The now-heated gas refrigerant is moved outside via insulated copper tubing. The compressor works to pump that refrigerant through the condenser coils. As this happens, the heat is transferred back out of the refrigerant. This is done in two different ways.

First, there’s an outdoor blower fan that forces outdoor air over the condenser coils to remove the heat. Second, there’s a series of small metal fins that are attached to the condenser coil. These help to disperse the heat that’s in the condenser coil. As the refrigerant loses its heat, it returns to a liquid state.

A Return Trip Through The Expansion Valve

As the liquid refrigerant makes its way back into your indoor unit, it enters through an expansion valve. This valve helps to remove pressure from the liquid refrigerant. It also helps to regulate how much of the refrigerant enters the evaporator coil. Once the liquid refrigerant enters the evaporator coil, it starts the process all over again.

Reliable AC Services

If you’re in need of air conditioning services in Puyallup, WA, Expert Air Control can help. We can assist you with all of your cooling, heating, air purification, duct cleaning, duct sealing, electrical, and gas piping needs. Give us a call today for more information or to schedule an appointment.

Categories: Air Conditioning