The Best Way to Defrost a Freezer

Written by: Paul Cathro

Updated on: November 30, 2020

When was the last time you defrosted your freezer? Maybe you have a modern frost-free freezer - but did you know they sometimes need defrosting too?


There are several causes of icy build-up inside a freezer, and we’re going to explain how to eliminate them, as well as how to defrost your freezer efficiently.

Why Defrost Your Freezer?

Every time you open the door of your freezer, you allow warm air in. Warm air contains more moisture, which means as it cools in your freezer, it creates frost. This frost can quickly accumulate into the dreaded wall of ice.

On the most basic level, a frosty build-up is irritating. It gobbles up precious space and can affect how your drawers operate.

In compartments, you can find that excess ice causes freezer-burn, meaning you’ll need to toss out the food you wanted to cook. If you wait too long, you might even struggle to get a proper seal on your door.

But it’s more than just a passing irritation.

If there is lots of ice, your freezer won’t be operating efficiently. It will be much harder for your appliance to stay cool, pushing your energy bills higher. If the door seal is not effective, the freezer is trying to freeze the whole room!

Trouble of refrigerator

It can be a safety concern too. When there’s a big problem you might notice that your food isn’t freezing properly. If your food isn’t freezing solid or is taking a long time to freeze, you’ll know right away that you have an issue.

In the early stages, you may be unaware that the freezer isn’t working efficiently. The temperature could be fluctuating, meaning that your food is freezing, partially defrosting, and then freezing again.  This can be the source of dangerous health issues.

Related: See which tiny freezers we think are perfect for small kitchens in our guide.

Why Frost Builds Up in a Freezer

Frost in your freezer is caused by moisture getting in. When it makes contact with the evaporator coils at the back of your appliance, it causes frost to develop inside.

There are several ways that moisture can enter a freezer, such as:

Wet food

Wet food introduces moisture to your freezer which can cool and turn into frost.

Hot food

Hot or warm food contains more moisture than cold food. If you put your food in the freezer while it’s still warm, you will cause humidity. This causes ice and frost to develop on the interior walls.

vegetables and meat in the freezer

Poor door seal

A tight seal is essential to keeping warm air out and cold air in. Over time, a door seal can degrade and start to “leak” air.

Not enough or too much food

Air circulating around the food helps to keep the food frozen and the temperature cold. If there is too much food, the air won’t be able to circulate, causing a build-up of frost.

Recommended: Ever wondered how to clean a freezer properly?

An open ice chute door

If your freezer has an ice chute built into the door, it can become wedged open if a chunk of ice gets stuck. This is a route for warm air, creating icy build-up.

Damaged defrost sensor

If you have a modern freezer that has an automatic defrost cycle, you shouldn’t need to defrost it. This process works via a sensor in the evaporator coils, which can detect when frost is starting to accumulate. When detected, the coils heat up, melting the ice and resolving the problem, before returning to regular mode.

If the sensor in the evaporator coils is faulty, it won’t trigger the defrosting process. The only way to solve the issue is by replacing the sensor. 

The opened freezer part of the fridge with many frozen packages

How to Defrost a Freezer

If you’ve got ice that’s built up in your freezer, you’re going to need to defrost it. The good news is that with modern appliances, freezer defrosting doesn’t take much time.

You will need to prep in advance. Make sure you have ready:

  • A cooler
  • A bowl of warm water with a squirt of unscented dish soap
  • A sponge or dishcloth
  • Paper towels
  • A spray bottle
  • Vinegar or baking soda

Once you’ve assembled the above, follow these steps:

  • Turn off your freezer first
  • Put any ice from the trays in a bowl and place at the bottom of the cooler
  • Take the food out of the freezer and stash it in your cooler, on top of the ice
  • Remove the detachable shelves and compartments and put in a sink filled with hot water. Add a squirt of dish soap but make sure it’s fragrance-free to prevent scent transfer to the food. Wash it thoroughly, rinse and leave to dry
  • Soak a dishcloth in the hot, soapy water and wipe over the ice
  • As the edges of the ice melt, you can pull it off in chunks. Never use a knife or sharp implement as you may damage your freezer
  • Once you have removed all the ice, give your freezer a clean
  • You can do this by combining warm water and vinegar in the spray bottle. Alternatively, use baking soda and warm water. Spray this solution in your freezer and wipe over with paper towels.
  • Dry your freezer thoroughly
  • Replace the shelving, then the food
  • Make sure you space the food out sufficiently. Throw away any expired or freezer-burned items
  • Switch your freezer back on

Although defrosting a freezer isn’t the worst task, with cold hands and melting ice, it’s not a lot of fun. It’s far better to try and avoid any frost build-up at all, which is what we’re going to look at next.

Related: What temperature should your freezer be set at?

How to Prevent Frost Build-up in a Freezer

There are several steps you can take to prevent frost accumulating in your freezer. These include:

Check your freezer door seal regularly

If the seal isn’t tight, warm air can get in and cause frost. Check your freezer for a damaged seal by holding your hand close to the seal. If you can feel cold air, your door seal is either dirty or damaged.

Try cleaning your door seal first but it may need repairing or replacing completely.

Only place cold food in your freezer

Warm food contains moisture which can introduce humidity as it cools, allowing frost to develop. Wait for food to cool before putting it in the freezer.

Dry food off first

Moisture introduced to the freezer is an opportunity for ice to form. If your food is wet, wipe it dry before placing it in the freezer. This often occurs with ice-cream, especially during the summer months. Drying the carton off first will reduce icy build-up.

Hand opening refrigerator

Don’t open the door more often than necessary

It may sound obvious but don’t open the door more than you have to. Think ahead to all the ingredients you’ll need while you’re cooking and get them from your freezer in one trip.

Having a freezer which is tidy and well organized will allow you to instantly lay your hands on whatever you need.

Store the right amount of food - not too much or too little

Frozen food helps keep the freezer cold, and cools warm air down quickly. If you don’t have enough food in your freezer, it will take longer for warm air to cool, giving it more opportunity to transform into frost and ice.

Conversely, too much food won’t allow air to circulate, keeping the temperature evenly distributed. This can lead to extra-cold patches where ice can develop as there’s little room for air to move.

About the Author Paul Cathro

Paul is an ex-HVAC engineer with 5 years 'in the trade'.

He acquired in 2022 and aims to make it the internet's most comprehensive HVAC resource for small homes in the next few years.

You can learn more about Paul's story here.

Browse his published work on the website here.

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