How Does an Air Conditioner Work?

How Do Air Conditioner Works Quick Guide

A popular question goes, how does an aircon work? An air conditioner in a car or a room in Singapore works through the collection of hot air out of a certain room and then processing it to produce cool air into the same room from which the hot air had been collected.

How an aircon works is made possible by five major elements:

  • Evaporator
  • Compressor
  • Condenser
  • Expansion Valve
  • Refrigerant


Parts of an Air Conditioner

Installations of air conditioners in Singapore primarily come in two forms, namely the window system and the split system, which is further categorized into central and mini-split systems. These two types are popularly referred to as window-type air conditioners and split-type air conditioners. No matter the form of installation, air conditioners are generally composed of four major parts such as the following:


An evaporator is a heat-exchanger coil designed to collect heat from the inside of a room by way of refrigerant gas. It is in the evaporator that the liquid refrigerant draws heat in and subsequently evaporates into a gas.
Some of the most popular refrigerant gases applied in air conditioning systems are hydrocarbons such as R-600A and R-290, hydrofluorocarbons or HFCs such as R-410A, and hydrochlorofluorocarbons, or HCFCs such as R-22. These gases absorb the heat out of the room and go to the compressor for further processing.


As the name implies, this is where the compression of refrigerant gases takes place. It is found in the outdoor unit, which is the component installed outside the building.


From the compressor, the vaporized refrigerant travels to the condenser, which converts it back to its liquid state and emits the heat outside. The condenser is also found on the outside unit of a split-type air conditioner.

Expansion Valve

The expansion valve, also called the throttling device, is installed between the condenser’s hot coils and the evaporator’s chilled coils. This component keeps track of the amount of refrigerant traveling to the evaporator.
In window air conditioning systems, the three components mentioned above are all located within a small metallic box installed in a wall or window opening.
These are the primary parts of an air conditioner. Let us now discuss how they function together to make an aircon function.


Working Principle of Air Conditioners

An air conditioning unit collects hot air out of a given room, processes it inside itself using a refrigerant, and a set of coils, then releasing cool air into the same room where the original hot air had been collected.
Several people believe that an AC releases cool air using machines installed within it, enabling it to quickly cool a space. However, that is a mere misconception. Air conditioners do not work through magic. Instead, they use chemical and physical phenomena efficiently to cool a room.
Here is a detailed process of how aircon works. When an air conditioner is switched on and set to the desired temperature, its thermostat automatically senses that the temperature you have selected and the temperature of the air in the room are different.
This hot air is absorbed through a grille located at the bottom of the inside unit and subsequently flows across some tubes through which a coolant fluid or the refrigerant is running. The liquid refrigerant draws the heat in and turns into a warm gas itself. Essentially, this is how heat is expelled from the air that touches the evaporator coils. Apart from absorbing heat, the evaporator coil is responsible for removing moisture out of the incoming air, helping dehumidify the space.
This warm gaseous refrigerant is then transmitted to the compressor. The compressor will compress the gas to raise its temperature. This high-pressure, warm gas then goes to the condenser. The condenser condenses this warm gas to turn it into liquid.
The refrigerant is already a hot gas as it reaches the condenser but instantly turns into a cool liquid since its heat is released to the outside through metallic fins. Thus, the refrigerant loses its heat when leaving the condenser and turns into a cooler liquid. Then this runs through a tiny hole in the copper tubing known as an expansion valve that regulates the flow of cool refrigerant liquid into the evaporator. Hence, the refrigerant returns to its point of origin.



Although all the parts of window-type air conditioners are installed within a single metal box, the process of cooling is still the same. The whole process is repeated again and again until your desired temperature is achieved. An air conditioner continuously collects warm air and releases it back into space until no warm air is left to cool.

If you need an expert in aircon repairs and installation, feel free to contact SOServices.