What Happens If You Don’t Defrost Your Freezer?

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By Elizabeth Masterman

Reading Time: 4 minutes

Defrosting the freezer is a tedious and time-consuming job many of us dread. Then there’s the hassle of where to put the food while you’re getting the job done. So, you may be wondering, is it a job that needs doing?

What Happens if You Don’t Defrost Your Freezer?

If you don’t defrost it, frost will build up, forming a thick layer of ice. This will not only take up space, but it will also mean your freezer has to work harder. This will make it more expensive to run and increase the wear on the working parts.

What Causes an Excessive Build-Up of Ice?

If you notice ice building up remarkably quickly, there could be a problem with the freezer.

Firstly, check whether the door has been left slightly open. This will often result in a visible patch of condensation outside the freezer, or even a puddle underneath the freezer door, where the ice has started to melt.

If you think the door has been left open, check the items in the freezer carefully, as things that have started to defrost will need eating as soon as possible.

Next, check the door seals, as inefficient door seals can let air in, increasing the moisture inside the freezer.

You can check this by opening the freezer door, placing a piece of paper over the door seal, and closing the door. If you can take the paper out without having to open the door, then the door seals need replacing.

Why Is It Important to Defrost a Freezer?

A thick layer of ice can take up space in your freezer. It can also stop the door from closing correctly, allowing more air in, leading to more ice forming, thus exacerbating the problem.

A build-up of ice can also cause an unpleasant, stale smell in the freezer.

Ice Build Up in a Freezer Shelf

Excessive frost in your freezer means that the appliance has to work harder. This means it will use more energy, making it less efficient and worse for the environment.

It will also cost you more to power it, particularly with prices currently at an all-time high. Having to work harder will also cause greater stress on the working parts of the freezers, reducing the life of the appliance.

If ice has built up particularly quickly, it could be a sign that something is wrong with your freezer, so defrosting it will enable you to see how quickly it frosts up again and better gauge if there might be a problem.

How Can I Avoid Frost Build up?

If frost is caused by moisture entering the appliance when the door is open, it makes sense to open the door as infrequently as possible and for as short a time as possible.

Think carefully about how you group items in the freezer so that you can find things quickly, meaning less time with the door open while you find what you are looking for.

Avoid Freezing Warm Foods

You also need to ensure that any cooked food has had the chance to cool down before you put it in the freezer.

Warm food creates steam which would then be trapped in your freezer, condensing and then freezing. Hot food can also cause the temperature inside the freezer to rise, causing the freezer to have to work harder to stay at the same temperature.

Do All Freezers Need Defrosting?

Frost-free freezers shouldn’t need defrosting. These modern appliances work in one of two ways.

As already explained, frost forms when warm air enters the freezer. Some modern appliances reduce frost by using a fan to blow this air away before it can condense and freeze.

However, if ice builds up around the fan, it can prevent it from functioning properly.

If you catch this problem early, unplug the appliance, remove the food, use warm water to melt the ice, and then wipe away any residue. You can then replace the food and switch the appliance back on, and it should then function as expected.

Other frost-free freezers have a defrost system that comes on periodically throughout the day to stop frost from building up.

The evaporator coils are wrapped in a heating coil with comes on briefly until the ice is melted. This system involved a timer, heater and thermostat, so a fault in any of these parts could cause ice to build up. This would need to be looked at by a qualified electrician. 

Freezer Coils

Can You Defrost a Freezer with Food Still In It?

If you are defrosting your freezer, remove all the food before starting. If you use the traditional method of switching the freezer off and leaving it with the door open to thaw in its own time, this will allow the food to thaw too. 

Frozen food must be kept at -18oC to keep it safe for consumption.

It’s OK to keep it out of the freezer for a short period, for example, when bringing frozen food home from the supermarket, but any longer than this, and it is likely the food will start to thaw.

If you use one of the faster methods, such as putting bowls or boiling water in the freezer, or using a hairdryer, then the heat is likely to cause the food to thaw.

When food starts to thaw, the bacteria and microorganisms that have been in stasis are allowed to multiply again, meaning that if the food is not consumed soon, it will become dangerous to eat.

Freezer Full of Food

If you have more questions about the importance of defrosting your freezer, check out these FAQs:

Why Does My Freezer Frost Up?

Every time you open the freezer door, warm air meets cold air, causing condensation, which then freezes, creating a thin layer of frost. Over time this builds up, forming a layer of ice. This is perfectly normal.

Will a Freezer Defrost Itself?

No, this will not happen. Some freezers have a feature that is supposed to prevent frost from building up, but these features don’t work 100% of the time. If there is frost, you’ll need to manually defrost it to clear it entirely.

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