How Does an Air Conditioner Work?

Carolina Evans
Carolina Evans
Research Writer
Holds a Master’s degree in Engineering and is keen on her own home’s climate. Sometimes we think that Carolina owns every single product she writes about – that’s ho read more
Reviewed By
Richard Powell
Richard Powell
Expert Consultant
For 8 years, Richard had been working as an HVAC specialist and AC unit installer since his student years. Now, he’s our main consultant on every technical aspect that may read more
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If you have ever asked yourself: “How does an air conditioner work?”, that’s what we’re here to find out. These devices aim to remove warm air from a room, blow out the cooled air while also reducing humidity. How they do that is both simple and ingenious.

AC units have been around for a long time now and have saved many people from having uncomfortable and sweaty homes and offices. They work in the same way as a refrigerator, but with the cooled air blow out into the room instead of into an insulated compartment.

They are far more effective than just a fan, which simply blows the same hot air around and simply relies on wind chill. An AC unit depends on a series of basic scientific principles to physically remove the hot air from the room. Here, we will look at how exactly an AC unit works and why people love this tried and trusted method of cooling down a room.

How does an air conditioner remove excess heat?

How Does an Air Conditioner Work?

There are four main parts when it comes to how an AC works, and you can describe them in any order, as they go around in a never-ending cycle. We’ll start with the area that cools the room down, and that is the evaporator.

Evaporator – They key ingredient of an AC is a chemical called a refrigerant. There are a few types available, but they are all incredibly good at absorbing and then dispensing the heat by switching from a liquid to a gas. They are able to do this a lot more efficiently than you could with water.

This liquid is pumped into the coil of the AC, where it absorbs the hot air around it. This then evaporates the chemical from a liquid into a gas. As this makes the air around the coil cooler, the fan then blows this cooled air into the room. The heat from the air inside the room is then transferred into the refrigerant, which has turned into a gas. This hot gas is then sent into the compressor.

Compressor – The compressor is the first stage in turning that gas back into a liquid. Here, the gas is compressed, which will give it an even higher temperature, and it will also mean that it now has a high level of pressure.

The compressor and the condenser are be located outside of the home, with only the evaporator being inside the home. Once the gas is compressed, it will be sent through to the condenser.

Condenser – A condenser works by turning the gas back into a liquid. As the gas is now hot and high-pressured, it will radiate its heat into the atmosphere. This is helped by a series of metal fins that will dissipate the heat.

As the refrigerant loses its heat, it will gradually turn back into a liquid. This will then get passed into the expansion chamber.

Expansion – This chamber will regulate the flow of the refrigerant into the evaporator, and this will depend on the thermostat. Once the cooled liquid is sent into the evaporator, then the whole process starts once again.

You can see the refrigerant as a train, which picks up heat from one stop and drops it off at another. The result is a room that has had a sufficient amount of hot air taken out, so it can now be comfortable.

Once the room reaches the desired temperature, the thermostat will automatically turn your AC off until it becomes too warm again.

Humidity control

How Does an Air Conditioner Work?

Another feature of AC units is their ability to remove moisture from the air. This isn’t a feature that can be turned off and on, it’s simply a part of how they work. It all happens on that evaporator coil where the refrigerant liquid turns to gas.

Due to the warm air around it and the cooler evaporator coil, water will condense on the coil, and therefore, this humidity is being removed from the air. AC units will then collect this water and remove it from the room.

It’s the same phenomenon that you see when you have a cold can of drink outside. The warm water vapor hits the cold can and turns into water. An AC unit uses this to reduce the humidity, but is that always a good thing?

When you exercise, your body cools down by sweating as the water on your skin will cool down more quickly than air. When humidity is very high, your sweat isn’t able to cool you down as efficiently, so you just stay hot and sweaty.

Less humid air is a lot more comfortable to be in. It also has quite a few health benefits that include reducing possible mold growth that can cause many allergic reactions.

An air conditioning unit is effective as it combines these two ways of cooling you into one. The warm water vapor is condensed into the water to reduce humidity, and the warm air is transferred to the refrigerant. Both are effective in creating a comfortable environment.


By now, your question “How does an air conditioner work?” should be answered. It simply transfers heat from inside your home and dumps it outside. The method in which it does this is fairly simple, but one that has been perfected to give you the ultimate control over your comfort.

Some units are a lot better at doing this than others. Also, larger machines have larger areas in which to cool down and heat up the chemicals and are therefore more effective.

If you’re wondering how a home AC unit works compared to the central AC unit, then they use the same method, just at different scales.

Before buying an AC, it’s a good idea to make sure you’re getting one that’s perfect for your needs.

When you do get one, you’ll now be able to tell people exactly how it works. Most people will just be happy that they can enjoy their day in a cool and comfortable environment.

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