An AC has become an essential device in most households. However, the functioning of this appliance is not known by many owners. This can be a problem as knowing how an AC operates will save you a lot of money and hassle.  You will be able to easily recognize any malfunction and make efforts to resolve it by yourself. Or, you will know if it’s time your AC needs to be serviced. At the very least, you will be able to understand what the technicians are doing and not get duped by them.

In this article, we will discuss the various parts of the unit, their functions, and the overall working of an air conditioner in a simple manner. 

Basic Principle of an AC Unit

The basic function of any air conditioner is to draw out the warm air from the room and add cooler air back into the room. Not just this, it removes any moisture content in the air which decreases the humidity in the room. This is why you don’t perspire in an AC room. 

The warm air that is drawn out is then released outside and cool air is released back into the room with the help of a chemical named refrigerant and a series of copper coils. This refrigerant is a chemical substance that can turn into gas or liquid. This change is vital in the cooling process of the AC.

The entire cooling process is done with the help of a compressor, condenser, fans, expansion valve, evaporators, and refrigerants along with a blower and thermostat. 

We will talk about all these in detail here. Stay till the end to understand the complete picture of the functioning of an air conditioner in detail.

Parts of an Air Conditioner:

1. Refrigerant:


A refrigerant is a very important part of the AC. It is a chemical substance that has the ability to absorb heat. It is the only moving part in an AC system as it continuously moves between various parts of the AC. 

During this movement, it continuously changes its state from gas to liquid and back to gas again to cool down the room. This process is explained at the end in detail.

Over the years many different kinds of refrigerants have been used in the AC. They are heavily regulated due to their harmful nature to the environment. 

Some of the Popular Refrigerants are:

HFCs: HFCs or Hydrofluorocarbons are the newest forms of refrigerant that are being used in the market these days. They do not have Chlorine in them and hence are considered relatively safer for the environment. They do not contribute to ozone layer depletion. However, their use is regulated by authorities as they remain a greenhouse gas that contributes to global warming. All the new models of ACs that use HFCs are refrigerants. The HFCs used in ACs are also popularly known as R410A due to their chemical composition.

HCFCs: HCFCs or Hydro Chloro Fluorocarbons came after CFCs and can still be found in some ACs. They were not as toxic as the CFCs for the environment but they still were quite damaging to the environment and were responsible for the depletion of the ozone layer. Over the years the Montreal Protocol agreement was amended to include HCFC as well. Their usage has been restricted and is in the process of being phased out. 

CFCs: CFCs or chlorofluorocarbons were popularly used as refrigerants when ACs first came to India but were soon banned after the Montreal Protocol in 1987, due to their high contribution to the greenhouse effect. 

2. Compressor:


The compressor as the name suggests compresses or adds pressure. It will compress or add pressure to the refrigerant to heat it up. This is important as this will change the temperature of the refrigerant gas to a hotter gaseous state . The temperature of the refrigerant has to be higher than that of the room for it to be able to move to the next stage. Compressor makes that possible.  

The refrigerant moves from the compressor to the condenser then to the expansion valve and then to the evaporator. After this, it again goes back to the compressor and the cycle continues. 

3. Condenser:


The condenser is situated on the outdoor unit of a split AC or the side that faces outside in a window AC. It has a series of copper coils along with a fan that pushes the heat to the environment. 

The refrigerant moves from the compressor to the condenser. The condenser is responsible for changing the state of the refrigerant from gas to liquid. Unlike, compressor, it does not change the temperature of the gaseous refrigerant. The temperature of the refrigerant remains hot, but the state changes from gas to liquid.

4. Fan:


There are two fans in an average AC unit. One is present in the condenser called the condenser fan which is in the outdoor unit and the other is present in the indoor unit inside the evaporator and is called an evaporator fan. 

The main function of the fan is to circulate and push out the air in the region. In the condenser, the fan pushes out the hot air to the outside environment and in the evaporator, the fan pushes out the cool air into the room. 

5. Expansion Valve:

Expansion Valve

The expansion valve is the opposite of the compressor. While the compressor compresses, the expansion valve expands the refrigerant molecules and reduces the pressure. But like the compressor, it changes only the temperature of the refrigerant, the state remains the same. It cools down the liquid refrigerant and also controls the flow of refrigerant to the evaporator. 

6. Evaporator:


The evaporator is situated in the indoor unit of a split AC and in a window AC, it is situated in the area facing towards the room. The evaporator contains coils in them which are called the evaporator coils. These coils are made up of copper. When the cool liquid refrigerant passes over the copper coils of the evaporator, it cools the entire evaporator, a fan then circulates and pushes this colder air out into the room. 

At the same time, due to the cool refrigerant, the evaporator becomes cooler than the room temperature. This forces the warm room air to travel towards the cool area of the evaporator. The evaporator then absorbs this warm air from the room while pushing the cool air into the room. 

7. Blower:


Blower acts as an aid to the fans. It is powered by a motor that causes the fan blades to revolve and dispense the air. Without the blower, the fans will not revolve and the air will not be properly released. 

8. Thermostat:


The thermostat detects the temperature of the room and adjusts the temperature accordingly. It is the brain of the AC, the thermostat stops the AC when the desired temperature of the room has been reached. It also turns on the AC once the temperature is higher than the desired temperature. It helps regulate the room temperature according to the temperature setting that you have selected. 

How Does Your AC Cools Down The Room:

  • First, the compressor starts adding pressure to heat the refrigerant. Here the refrigerant will get heated to become hotter than the room temperature.
  • Now, the hotter gaseous refrigerant will travel to the condenser coil where the refrigerant will change its state from gas to liquid but the temperature remains the same i.e. it is still a warm liquid.

This is done because the heat energy is absorbed from the gaseous refrigerant and a fan blows the warm air out to the environment. As the warm air blows out of the unit, the gaseous refrigerant cools down and condenses into a liquid. 

  • Now the high-temperature liquid refrigerant travels to the expansion valve, the expansion valve will reduce the pressure of the hot liquid refrigerant by expansion, and cool them down. It will also regulate the amount of cool refrigerant liquid that flows to the evaporator coil.
  • The evaporator coil will now become cooler due to the cold refrigerant liquid, this will cool the evaporator and the fan then pushes this cool air out into the room.
  •  At the same time, the warm air of the room will travel towards the evaporator because the heat always moves from a warmer to a colder region. The warm air will get absorbed into the evaporator at the same time cool air is being thrown out from the evaporator. 

After absorbing the heat from the room, the de-pressurized gaseous refrigerant again moves towards the compressor which compresses it and the process repeats in a continuous loop to remove hot air and add coolness to the room.