How Does a Fridge Work?

How does a fridge work? Samsung fridge showing cool air

Have you ever stopped to think “how does a fridge work?”

The household refrigerator is a commonplace appliance. Because of this, it’s easy to forget that there’s actually some clever mechanisms within. This allows us to keep our food cold, fresh and tasty!

The way it works is by using some scientific laws involving pressure and evaporation. In this guide we’ll explain how a fridge works to keep our food cold.

How Refrigeration Works

The Air Conditioning Working Principle

This is the basic scientific premise behind how refrigerators and air conditioning units work. This includes things from mini bar fridges, to central heating, to fans in a car.

The scientific principle behind it is that warm air gets replaced by cold air. This is done through the process of evaporating and condensing something called refrigerant.

We will explain exactly how this works in your fridge using the main fridge components.

The Five Main Components of a Fridge:

  • Compressor
  • Condenser
  • Expansion Valve/Capillary Tubing
  • Evaporator
  • Thermostat/Temperature Gauge

What is a Refrigerant?

Refrigerants are used in both air conditioning units as well as fridges. They are in either a fluid or gaseous state, depending on where in the process they are. Refrigerant is essential for your fridge to create a cold temperature, keeping food fresh.

How Does a Fridge Work?

So, how does a fridge work? A fridge works by taking refrigerant through a cycle all around the fridge. During this process, the refrigerant is heated up and cooled down, turning from a gas to a liquid – and then back again. The full cycle is detailed below, explaining how the process actually cools down your fridge.

  • Step 1 – The Compressor

The compressor pumps in cold and low pressured refrigerant in a gaseous state. Then, the refrigerant is compressed. This compression heats and pressurises it.

  • Step 2 – The Condenser

The hot and high pressured refrigerant is then channelled into the condenser. The condenser removes the heat and condenses the gas into a liquid.

Ventilation Fins: The heat that is removed from the refrigerant is then released through cooling fins at the back of the fridge. This is why the back of your fridge can get quite warm, or even hot!

  • Step 3 – The Expansion Valve

Then, liquid refrigerant is pushed through the expansion valve. Within this chamber, the pressure is suddenly dropped. This sudden drop in pressure causes the liquid to expand, with some of it rapidly turning into vapour. This change of state from liquid to gas has a cooling effect on the surrounding area.

  • Step 4 – The Evaporator

Afterwards, cold refrigerant in a liquid state leaves the expansion valve and enters the evaporation coils. As it travels through, it absorbs any warm air inside of the fridge. Because refrigerants have low evaporation points, this absorption turns it back into a gas, therefore evaporating. This process has a cooling effect that keeps your fridge nice and cool.

Finally, the cold and low pressure gas from the evaporator travels back into the compressor to begin the cycle again.

How does a fridge work - Appliance City

Should you clean the back of your fridge?

It’s important to clean the back of your fridge because this is where your condenser coils are. When they are covered in dust, fur, or other debris, they do not perform as efficiently. That’s because these will trap the heat that is trying to escape.

Learn more here: How to Clean Condenser Coils

What Type of Gas Does a Fridge Use?

Fridges use a type of gas called refrigerant. However, many different types of refrigerants have been used since the first household refrigerator was invented in 1913.

The first refrigerants used are known as hydrocarbons. Isobutane and propane are examples of these. These were then replaced with chlorofluorocarbons (CFCs). However, CFCs were replaced by hydrofluorocarbons (HFCs) after CFCs were discovered to deplete the ozone layer.

Since then, many manufacturers across Europe, Asia and South America have gone back to using hydrocarbons. This is because HFCs were also found to be detrimental to the planet’s health.

Therefore, although hydrocarbons depend on non-renewable resources for their existence, they are currently the most environmentally friendly refrigerants.

A black fridge compressor inside of a fridge, showing how a fridge works


  • How does a fridge water dispenser work?

How a fridge water dispenser works will depend on if the model is plumbed or not. Non-plumbed fridges with water dispensers will have an interior water reservoir. These are removable so that you can fill them easily. Plumbed fridges, on the other hand, are connected to a main water supply. This allows the fridge to tap into a cold water source, so you can receive water directly from the fridge without the need to refill. Fridges will often have a water filter and/or softener to give you a better drinking experience.

  • Is there such a thing as a frost-free fridge?

No, there is no such thing as a frost-free fridge. This is because a fridge should never reach temperatures cold enough to produce frost. If it does, you should adjust the settings on your fridge.

Need more information?