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How Does an Air Conditioner Work?

How Does an Air Conditioner Work

Air conditioners have become essential to our lives, especially during summer. It not only provides comfort but also helps improve air quality.

But have you ever wondered how does an air conditioner work? In this article, we will understand the basic working principle of air conditioners. Let’s get started. 

What is an Air Conditioner?

An air conditioner is a machine that cools and dehumidifies the air in a room or an area. It removes heat and moisture from the air and circulates cool and dry air back into the room.

Understand the Basic Components of an Air Conditioner

An air conditioner has four main components: a compressor, a condenser, an evaporator, and an expansion valve. The compressor compresses the refrigerant, which then flows through the condenser, releasing heat to the outside. The cooled refrigerant flows through the evaporator, absorbing heat and moisture from the air. 

The expansion valve controls the refrigerant flow into the evaporator, regulating the amount of refrigerant that enters the system. This valve also affects the pressure and temperature of the refrigerant, which affects the overall cooling process.

By understanding these basic components and their functions, homeowners can troubleshoot and diagnose problems with their AC units and ensure proper maintenance.

Step-by-Step Guide on How an Air Conditioner Works

An air conditioner removes heat and humidity from the air in a room or building. The whole process is known as refrigeration. 

1. Refrigeration Cycle

The refrigeration cycle is used in air conditioners to remove heat from a particular space or area and transfer it to the outside environment. 

The cycle involves four main steps: compression, condensation, expansion, and evaporation. These steps are repeated continuously to maintain a cool and comfortable indoor environment.

A step-by-step breakdown of the cycle:


Compression is the first step in the refrigeration cycle. In this step, a compressor compresses the refrigerant gas, which increases its temperature and pressure. The high-pressure gas is then transferred to the condenser.


In the condensation step, the hot and high-pressure refrigerant gas is cooled down by passing it through the condenser. The refrigerant gas condenses into a high-pressure liquid, releasing heat to the outside environment. The liquid refrigerant then moves on to the expansion valve.


The expansion valve is the third step in the cycle. During this step, a liquid with high pressure passes through the small orifice (valve), where its pressure and temperature decrease. The low-pressure liquid refrigerant moves on to the evaporator.


Evaporation is the final step of the process, where the low-pressure liquid evaporates as a gas that helps absorb the indoor environment heat. The cooled gas is then returned to the compressor to start the cycle.

2. Air Distribution and Cooling

The air distribution system is a network of ducts and vents circulating air throughout a building. It distributes conditioned air (heated or cooled) to different building areas.

Blower fan:

The blower fan is a crucial component of the air distribution system. It is responsible for circulating air through the ducts and vents. 

The fan draws in air from the return ducts and then blows it over the evaporator coils or through the furnace heat exchanger to condition it. The conditioned air is then released through the supply vents.

Evaporator coils:

The evaporator coils are a set of coils responsible for cooling the air. They are located in the air conditioning unit and work by removing heat from the air as it passes over them. 

The coils contain a refrigerant that absorbs the heat from the air, causing it to cool down. The cooled air is then circulated through the air distribution system.

3. Thermostat and Temperature Control

A thermostat is a device used to regulate the temperature of a room or building. Its purpose is to maintain a comfortable indoor environment by controlling the heating and cooling system in response to temperature changes.

The thermostat monitors the room’s temperature through a sensor and compares it to the desired temperature set by the user. If the temperature is too high, the thermostat will signal the air conditioning system to turn on and cool the room.

If the temperature is too low, the thermostat will signal the heating system to turn on and warm the room. The thermostat signals the air conditioner to turn on/off through a relay.

When the temperature in the room reaches the set point, the thermostat sends a signal to the relay, which then turns the air conditioner on.

Similarly, when the temperature falls below the set point, the thermostat sends a signal to the relay to turn the air conditioner off. This process keeps working in a cycle until the room temperature reaches the desired value and gets maintained.

Types of Air Conditioners

There are many types of air conditioners. Some popular are: 

Window Air Conditioners

Window air conditioners are the most common type of air conditioner designed to fit inside a standard window frame. They are suitable for cooling small to medium-sized rooms and are relatively easy to install.

Central Air Conditioners

Central air conditioners are more expensive but designed to cool an entire house or building. They use ductwork to distribute cool air throughout the space and can be more energy-efficient than window units in larger spaces.

Portable Air Conditioners

Portable air conditioners are versatile as you take them from one room to another. They do not require installation in a window and can be a good choice for renters or those who don’t want to make a permanent installation. However, they may not be as powerful as a window or central air conditioners and can be noisy.

Benefits of Having an Air Conditioner

There are many benefits of having a conditioner:

Improve Air Quality:

Air conditioners help improve indoor air quality by filtering dust, dirt, and other pollutants. AC units come equipped with air filters that trap harmful particles such as pollen, pet dander, and mold spores, thereby preventing them from circulating. This is especially beneficial for individuals with allergies or respiratory problems.

Increase Comfort:

Air conditioners regulate the temperature and humidity level of our homes and offices’ indoor environment to provide comfort. They remove excess heat and moisture from the air, creating a cool, dry atmosphere conducive to relaxation and productivity. 

This is especially important during hot and humid weather conditions when staying indoors can be uncomfortable.

Reduce Humidity Levels:

High humidity levels can cause discomfort, promote the growth of mold and mildew, and damage indoor furnishings. 

Air conditioners remove excess moisture from the air, which helps to reduce humidity levels and prevent these issues. This is particularly important for individuals living in areas with high humidity levels.

Noise Reduction:

Air conditioners can also help reduce noise levels in the home. AC units provide a relaxing atmosphere conducive to sleep and rest by creating a cool and comfortable environment. 

Additionally, many modern air conditioners are designed to operate quietly, making them an ideal choice for bedrooms or other areas where noise levels must be minimal.

These benefits make air conditioners an important investment for creating a comfortable and healthy indoor environment.

Frequently Asked Questions 

How does an air conditioner improve indoor air quality?

Air conditioners come equipped with air filters that trap harmful particles such as pollen, pet dander, and mold spores, preventing them from circulating. This is especially beneficial for individuals with allergies or respiratory problems.

How often should I clean the filters of my air conditioner?

It is recommended to clean your air conditioner’s filters once every month during the summer. However, the process of cleaning is more frequent if you have pets or live in a dusty area. 

How can I reduce the noise levels of my air conditioner?

Many modern air conditioners are designed to operate quietly. However, you can further reduce the noise levels by installing the AC in a shaded area away from direct sunlight and obstructions. You can also opt for a unit with a noise reduction feature.

Can I install an air conditioner myself?

It is recommended to get the air conditioner installed by a professional technician to ensure proper wiring and drainage. Improper installation can lead to inefficient operation and even damage the unit.

How often should I get my air conditioner serviced?

Getting your air conditioner serviced at least once a year is recommended to ensure its smooth and efficient operation. Regular servicing can also extend the lifespan of your AC and save you money on energy bills.

Can low refrigerant levels damage my air conditioner?

Yes, low refrigerant levels can cause the AC to work harder and can eventually damage the compressor. It is important to check and refill the refrigerant levels regularly.


Air conditioners are essential to our lives, especially during the warm weather. Understanding how they work and how to maintain them can help us enjoy their benefits for years to come. 

This information lets you make informed decisions when buying, installing, and maintaining your air conditioner.