Exactly How Does An Aircon Work?

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How would you answer the question: How do air conditioners work? If you are like most people, you would say that it produces cold air, which it then blows throughout the house. However, most people are surprised to learn that air conditioners don’t actually produce cold air at all.

What air conditioners actually do is displace the hot air in your home, transferring it outside. This seems counterintuitive since we can actually feel cold air blowing upon us if we put ourselves in front of the air vent. Which is something that I think we all experience regularly!

How Exactly Does an Air Conditioner Work?

In a nutshell, this is the process: the hot air inside your house is absorbed through a special chemical coolant that runs through coils in your air conditioning unit. The coolant is run from your home to the air unit outside, where it is then transferred and sent back to your home.

There are special features that allow the coolant to either collect or release the heat at the right intervals. These include the evaporator, the compressor, and the air condenser.

If you are like most people, this explanation opens more questions than it answers, so let’s look a little deeper.

Stage 1 – Absorbing the Heat From Your Home

The first part of the process is absorbing heat into the evaporator coil. The hot air is pulled through a grill that is placed at the base of the unit.

The hot air is then blown outside through a vent that blows over your evaporator coil. The evaporator coil resembles a car radiator. If you have a window unit, it is the back part of the unit. If you have an HVAC system in your home, then the coil is most of the large box alongside your house in your yard.

While the air blows over the coil, it causes a reaction known as latent heat transfer or the heat of transformation. Without boring you with the scientific explanation, it has to do with the cooling effect of evaporation.

Basically, when the coolant is cool, it is eighty percent liquid and twenty percent gas, but it is completely converted to gas when it heats up. The air conditioning unit takes advantage of physics and plays on this transformation to either absorb or expel heat from the liquid.

It refers to the heat that a unit of mass evaporates. In the process of evaporation, no change in temperature is recorded, but the heat is transformed to vapor.

Once the cooling refrigerant is transformed completely into a vapor state, it then goes through a process of superheating. Once the vapor makes the full cycle back to the compressor and goes through the condenser, it is transformed back into the original consistency of eighty percent liquid and twenty percent vapor. Being, once again, a low-pressure refrigerant, it can start the process all over again, continuing to cool the air that passes through the air conditioning unit.

How does it do that? Take a look at the second stage below for the answer.

Stage 2 – Raising the Temperature

The temperature is raised when it is forced through the compressor. This decreases the gas’s volume and prepares it to condense. When it passes through the tubes where the warm air from the house is blown across the tubes, it absorbs the heat.

As the coolant heats up, it converts to one hundred per cent gas. Once this happens, it is ready for the third stage of the process.

Stage 3 – Transfering the Heat Outdoors

Once the coolant is vapor gas state, it reaches the outdoor condenser. The heat outside actually absorbs the heat in the coolant, which lowers its temperature and pushes it back to its eighty per cent liquid and twenty per cent gas state.

The cold air that is produced during the process is pushed through the vent. Eventually, all of the hot air is removed from the building.

Stage 4 – Repeating the Whole Process

Now that the coolant is in its liquid state, it is once again capable of absorbing heat. It obviously wouldn’t work well if it absorbed the heat from outdoors, which is why it is immediately pushed back inside, where the process repeats itself once again.

The process continues until the thermostat communicates that the desired temperature has been reached. Once the temperature is right, the air conditioning system shuts off until the temperature is raised once again. At that point, everything starts up again.

What About Evaporative Air Conditioners?

Evaporative air coolers work on a very similar principle, albeit much simpler. They basically suck in warm air and push it by a water source in order to cool it off. It is then blown back into the room. There are two different types of evaporative air coolers: direct and indirect.

Direct air coolers are called “direct” because they have direct contact with the water source. Usually, a type of wet sponge that the air is blown directly upon. This causes the air to be cooled down and blown back into the room.

Indirect air coolers don’t have direct contact with the water, but they use tubes similar to traditional air conditioners. The main difference is that the tubes contain water instead of a chemical coolant.

Evaporative air coolers are much more economical than traditional air conditioners. They are also much more environmentally friendly than traditional AC units. But, they come with a couple of catches.

For example, they are not near as efficient at removing the heat from a room. Another main disadvantage is that instead of removing the humidity, they may actually increase the humidity in a room.


After this article, you surely have a much better grasp of what exactly an air conditioner does. The next time you put your face in front of the AC vent in order to cool off, this will give you a lot to think about. Of course, if your AC unit starts to act up, a basic understanding of how it works may also help you understand what is necessary to fix the AC.

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