How Do Air Conditioning Systems Work?

Willis Haviland Carrier was a successful engineer. After graduating from Cornell University’s electrical engineering department in 1901, he started working at Buffalo Forge Company. One of his first projects here was to determine how much heat the air can absorb when passed through a system of heating coils.

Sackett-Wilhelms Lithographing and Publishing realized that in 1902, ammonia could be used in heat exchange to solve the problem of heat and humidity in the printing factory, and the first air conditioner was invented. This air conditioner weighed about 30 tons. Carrier and his team started R & D work on developing this functional machine and continued to work on the development of air conditioners that allow heat transfer from indoor to outdoor areas with substances such as ammonia, methyl chloride, and propane.

But the main breakthrough of “cooling” devices was the invention of refrigerants (refrigerants). Unlike ammonia and others, refrigerants were higher efficiency less harmful, and lower enthalpy products.

R22, R11, R12, R134-A were the first refrigerants that were invented in the General Engine Laboratory in just 3 days in 1928. It was commercialized under the name “Freon” after the patent of Dupont firm. By the end of 2019, its production has ceased worldwide. 103 types of refrigerants are actively used today.

We will go into the details of refrigerants in another article. It should be surprising that the air conditioning industry, which has a global volume of approximately 100 billion dollars today, is still operating with the same system today.

So how does an air conditioner cycle happen?

Air conditioners transfer the heat absorbed from the interior to the atmosphere. By transporting the temperature difference between the compression and expansion of the refrigerant between the spaces, this process not only provides us comfort but also allows our food products to be stored for a long time without spoiling and smelling. Below is a detailed diagram of the air conditioner conversion.

The following parts in detail are required for the healthy operation of this system, which consists of 4 elements.

Indoor unit:

  • Serpentine
  • Distributor
  • Expansion valve
  • Fan
  • Flaps
  • Flap motors
  • Electronic card
  • Control unit

The outdoor unit:

  • Serpentine
  • Expansion valve
  • Outdoor unit distributor
  • Engine
  • Capacitor
  • Electronic card
  • 4-way valve
  • 4-way valve solenoid valve
  • Outdoor unit fan

Pipe connection:

  • Suction line
  • Pressing line
  • Signal cable
  • Drain line

Air Condition Types

There are mainly 5 types of air conditioners, which are available in… types according to the decorative needs of the locations.

  1. Wall type
  2. Hall type
  3. Cassette type
  4. Floor-ceiling type
  5. Tile type
  6. Channel type

The indoor unit types, which are selected according to the needs and decoration of the location, change and develop day by day for the comfort of the users.

Today, the most deadlocked street of the industry is that advertising budgets are 3-4 times higher than the R&D budget. In the air conditioning sector, whose R&D budgets are far below the turnover-profit-advertising expenses, a revolutionary solution has not been found, although it is aimed to reduce energy consumption and increase efficiency with the spread of central systems, the development of motor systems, the design of the architecture for air conditioning in the next 10 years.

Components of How the Room Air Conditioning System Works

A set of AC tools or components including a compressor, condenser, orifice tube, evaporator, expansion valve, and evaporator with the following explanation:


The compressor is the power unit of an air conditioner system. When the air conditioner is running, the compressor changes the working fluid/refrigerant in the form of gas from low pressure to high-pressure gas. High-pressure gas is then passed to the condenser.


The condenser is a device used to convert/cool a high-pressure gas into a high-pressure liquid. The liquid is then drained into the orifice tube.

Orifice Tube

where the high-pressure liquid is lowered in pressure and its temperature becomes a cold low-pressure liquid. In some systems, apart from installing an orifice tube, an expansion valve is also installed.

Expansion valve

The expansion valve is the most important component of the system. It is designed to control the flow of coolant through the orifice valve which changes the form of liquid to vapor when the coolant leaves the expansion valve and enters the evaporator/coolant.

Evaporator / cooler

The refrigerant absorbs heat in the room through the cooling coil and the evaporator fan blows cool air into the room. The refrigerant in the evaporator begins to change back to low-pressure vapor, but it still contains a small amount of liquid.

The refrigerant mixture then goes into the accumulator/dryer. It can also act as a second orifice for the liquid to turn into pure low-pressure vapor, before passing through the compressor to gain pressure and circulate in the system again.

Usually, the evaporator is fitted with silicone which functions to absorb moisture from the refrigerant.

Description of How the Room Air Conditioning System Works


The compressor in the cooling system is used as a tool to compress the working fluid (refrigerant), so the refrigerant that goes into the compressor flows into the condenser which is then compressed in the condenser.

In this part of the condenser, the compressed refrigerant changes the phase from the vapor phase refrigerant to the liquid phase refrigerant, so the refrigerant releases heat, which is the heat of evaporation contained in the refrigerant.

The amount of heat released by the condenser is the sum of the required compressor energy and the heat energy taken by the evaporator from the substance to be cooled.

In the condenser, the refrigerant pressure in the condenser pipes is relatively much higher than the refrigerant pressure in the evaporator pipes.

After the refrigerant passes through the condenser and releases the heat of evaporation from the vapor phase to the liquid phase, the refrigerant is passed through the expansion valve, in this expansion valve the refrigerant pressure is lowered so that the refrigerant changes conditions from the liquid phase to the vapor phase which is then flowed to the evaporator.

In this evaporator, the refrigerant will change its state from the liquid phase to the vapor phase, this phase change is caused because the refrigerant pressure is made in such a way that the refrigerant after passing through the expansion valve and the evaporator the pressure drops significantly.

This can be practically done by means that the pipe diameter in the evaporator is relatively larger than the pipe diameter in the condenser.

With the change in the refrigerant conditions from the liquid phase to the vapor phase, to change it from the liquid phase to the vapor phase, this process requires energy, namely evaporation energy, in this case, the energy used is the energy in the substance to be cooled.

By taking the energy taken in the substance to be cooled, the enthalpy [*] of the substance to be cooled will decrease, with the decrease in the enthalpy, the temperature of the substance to be cooled will decrease.

This process will change continuously until there is cooling as desired.

With this electric cooling machine, it can be easily done to cool or lower the temperature of a substance.

Need to know :

The key to air conditioning is the refrigerant, which is generally fluorocarbon [**], which flows in the system, becomes a liquid and releases heat when pumped (under pressure), and becomes a gas and absorbs heat when the pressure is reduced.

The mechanism of changing the refrigerant into a liquid and then a gas by giving or reducing pressure is divided into two areas: an air filter, a fan, and a cooling coil on the side of the room and a compressor (pump), a condenser coil (heat exchanger coil), and a fan on the outside window.

Hot air from the room passes through the filter, leading to the cooling coil which contains cold refrigerant liquid, so that the air cools, then through the trellis/lattice back into the room.

In the compressor, the refrigerant gas from the cooling coil is then heated using compression. In the condenser coil, the refrigerant releases heat and becomes liquid, which circulates back to the cooling coil. 

Passive Cooling!

Maybe you are frowning at the moment reading the word above, is that passive cooling? Thought you. So maybe this has nothing to do with how AC works, even though we have some tips to keep your house cool even without air conditioning.

There are several ways you can take to dissipate the heat hitting your home, and we call it passive cooling.

Some of these ways are to use the environment to create shade, for example by planting trees around the house. Another way is to use dark exterior paint color, use a radiant barrier on your roof, or use other insulators.

Another simple way is to use the principle of thermal siphoning. You can do this by opening 2 windows in opposite directions. One of them is the window that is located below, and the other that is located above. This creates a vacuum which in turn can carry hot air outside.

Share your love