Freezers are one of the most important of all kitchen appliances. Without freezers, we’d be back to preserving foods through dehydration, spicing, and canning. But how many people know how a freezer works? Explaining the answer to the question: How does a freezer work? is what we’ve set out to do here!

So How Does a Freezer Work?

A freezer works by compressing and then expanding a substance called a refrigerant from a liquid to a gas and then back again. When this happens, heat is exchanged from the freezer coils to heat-radiating coils on the bottom or back of the freezer. We’ll go into more detail below, but that’s the basic idea behind most home refrigeration units.

There are several ideas that go into understanding the question how does a freezer work. For example, how does a frost-free freezer differ from one without this feature? Or, how can I make my freezer operate more efficiently? Read on, and we’ll answer these questions and more.

The Inner Workings of a Freezer

In a freezer system, there are five basic components: the fluid refrigerant; a compressor with the condenser coils outside the freezer; the evaporator coils inside the freezer; and an expansion device. Let’s discuss these components individually.

Fluid Refrigerant

A fluid is a substance without a fixed shape that can flow rather than stay in one place. A fluid refrigerant is a substance that can be compressed into a liquid or expanded into a gas within the temperatures and pressures available in your freezer’s cooling system.

Until a few decades ago, the most common fluid refrigerant was called Freon. But Freon was banned because of its harmful effect on the ozone layer. Today’s most popular fluid refrigerant for freezers and refrigerators is called HFC-134a. This is easier to say than its chemical name, which is 1,1,1,2-Tetrafluoroethane. So now you know!


Understanding how does a freezer work requires learning what the compressor does. The name alone should give you an inkling of what function it performs. The freezer’s compressor compresses the fluid refrigerant and pumps it throughout the freezer’s cooling system.

The compressor is an electric motor connected to a pump. When it comes on, that’s the humming noise you hear. The intervals between the compressor’s cycling on and off depend on how low you’ve set the freezer’s thermostat. The lower it’s set, the more often the compressor will run.

Condenser Coils

The condenser coils are long, thin tubes that snake around the back or bottom of your freezer. Their function is to radiate the heat produced when your freezer compartment is cooled by the system into your environment.

Evaporator Coils

Your freezer’s evaporator coils are the opposite of the condenser coils. They are thin tubes that wrap around the inside of your freezer compartment. Their job is to take heat out of your freezer compartment and pass it to the condenser coils, where the heat can be radiated away.

Expansion Device

The expansion device (or expansion valve) is a nozzle within the cooling system. When compressed liquid refrigerant passes through the nozzle, it expands back into a gas.

How They Work Together

Now that you understand the components of the cooling system, Let’s look at how they work together to cool your freezer. First, the physics of the heating/cooling cycle.

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The Heating/Cooling Cycle

You may recall that when you spray an aerosol onto your hand, it feels cool. This happens because the pressure inside the aerosol can keeps the propellant in liquid form. When you release the propellant by pushing on the valve, the liquid propellant goes back into gaseous form.

When gasses compress into liquids, they release heat. Conversely, when liquids evaporate into gasses, they collect heat. So the aerosol gas is collecting heat from your hand as it expands.

Making Your Freezer Cold

This expansion/contraction cycle is how your freezer keeps cold.

First, the compressor in your freezer’s cooling system compresses the fluid refrigerant into a liquid. That liquid is then pumped through the condenser coils on the back or bottom of your refrigerator where some of the heat it contains is radiated away.

Now, the liquid refrigerant goes through the expansion device, which causes the liquid to become a gas. This gas is then pumped through the evaporator coils where it collects heat from the inside of your refrigerator compartment. This cools the inside of your compartment down to the temperature you have set the thermostat to maintain.

That’s the basics of how your freezer’s cooling system keeps your food frozen!

Making Your Freezer More Efficient

How can you make your freezer more efficient? This is a good topic to discuss since the more efficient you can make your freezer, the less energy it will use and the lower your electric bill will be. Here are some ideas to make that happen.

Clean Your Condenser Coils

Dust is an insulator. The more dust you have on your condenser coils, the less they’ll be able to radiate heat, and the more often your condenser will run. Your freezer’s owner’s manual will tell you how.

Check Its Temperature

Your freezer should maintain a temperature of between zero and five degrees Fahrenheit. Any colder and you’re wasting energy.

Don’t Block the Condenser Coils

Make sure you leave some space between your freezer’s condenser coils and the wall. The condenser coils need unrestricted airflow around them to operate efficiently.

Frost-Free Freezers

Most freezers today, especially if they are part of a refrigerator/freezer combination, are frost-free. How does that work, and what does it mean?

Frost-free freezers have a heating element inside them that comes on one to four times per day. This melts frost from both the evaporator coils and the inside of the freezer department. The liquid water then drains out of the freezer to an evaporation tray below the freezer where it evaporates into the air.

If you’ve ever wondered why your ice cubes become smaller over time inside your freezer, now you know.


You now have learned how your freezer, that amazing, labor-saving device, operates. You’ve also learned about how to make your freezer operate more efficiently. Remember, knowledge is power!

Last update on 2021-10-28 at 06:24 / Affiliate links / Images from Amazon Product Advertising API