How Do Indoor Air Conditioners Work?

Today, air conditioners have become one of the widely used electronic devices. They are the essential components of central heating and cooling systems in businesses, homes, offices, and other large buildings. There can be many kinds of air conditioners, but they all fall into two categories, window AC systems and split AC systems.

Air conditioners do come in various shapes, designs, and sizes. However, they follow a basic working principle which is to provide cold air to the area they are installed in while removing the warm air.

So, for example, if an air conditioner is installed in a room, it will remove the hot air/humidity from the inside and transfer it outside, ultimately making the room colder.

After being cooled, the air is returned to the indoors with the help of a sheet metal ductwork through a scientific process by using a specialized chemical which is called “refrigerant.”

How Does Air Conditioning Work?

Regardless of the types, all air conditioners work on the same principle, which is to blow hot air outside and blow cool air into the room. In this working principle, four main components are involved, which are present in every air conditioning system. These four components are:

  1. Evaporator
  2. Compressor
  3. Condenser
  4. Expansion Valve

All of these components work together in the working of an air conditioner. To understand in detail how do air conditioners work, let’s look at how all of these components play their part in the process.


The first thing that happens during the process is that the heat from the indoors is collected. This is done as a result of a special chemical called refrigerant. The evaporator acts as a heat exchanger coil. The refrigerant present in the evaporator helps to collect the heat from the indoors and then evaporates into a gas. Hence the name “evaporator.”

There are many refrigerants that can be used in an air conditioning system to collect the heat from indoors. However, the most commonly used refrigerants are R-410A, R-22, AND R-290. The initial step is to collect the heat, which is done by the refrigerant, and then it is sent to the next component for processing it further.


After passing through the evaporator, the refrigerant is then go by to the compressor. The compressor is generally found in the outside unit of the air conditioner. What the compressor does is that it simply compresses the gas (refrigerant is gaseous form) and sends it to the next component for further processing.


After the evaporated refrigerant is compressed in the outdoor unit, it is then transferred to the condenser. The condenser is also placed inside the outdoor part. In the condenser, the evaporated refrigerant is converted back into liquid. Moreover, the heat is then transferred outside.

Expansion Valve

The expansion valve is another important component of the cooling system. The expansion valve is responsible for controlling how much refrigerant passes through the evaporator. It is usually located between the evaporator cooling coils and the condenser heating coils.

In split ACs, the components are present in both the inside unit and the outside unit, but in window ACs, they are all present in a metal box in a window opening.

The Basic Working Principle of Air Conditioners

Air conditioners work by combining the elements as explained above. All the types of air conditioners, no matter what size they may be, work on the same principle. It works by accumulating hot air from the room, treating it with the help of a refrigerating agent, and then releasing cold air into the room.

The air conditioner itself does not produce cold air, but with the help of a refrigerating agent, a couple of coils, and a few chemical and physical processes, it gives cooled air.

When you set a particular temperature on your individual air conditioner, or the central cooling system, the thermostat that is installed in the AC detects that the temperature of the room and your desired temperature are different from each other. After that, the process of cooling air begins.

The exact process is done again and again within the outdoor unit and the indoor unit. It keeps producing cool air until the inside temperature becomes equal to the temperature you have set on the air conditioner. The cold air that is produced with every process is then circulated outwards with the help of a fan installed within the system. In this way, the cool air reaches everywhere in order to raise the temperature of a particular room.

Warm air is sucked in each process and decreases with every cycle, and when there is no hot air left in the room to cool down and the optimum temperature is reached, the air conditioning process stops.


Knowing how indoor air conditioners work saves you from a lot of hassle as you can detect and solve minor issues yourself. The same goes for maintenance; by knowing the process, you will use the indoor air conditioners effectively, and it will last longer than usual.

Thus, this article provides you some valuable information; it’s upon you to grasp it by reading it thoroughly and sharing it with others so we all know how indoor air conditioners work and how we can take the most benefit out of it.