How Does Auto Defrost Work on A Fridge Freezer?

Are you interested in upgrading your fridge/freezer combo to an appliance with auto defrost? Maybe your appliance already has this feature and you wonder how it works. We've done the research to better understand auto defrost on a fridge/freezer, so the next time you peek into the fridge/freezer you'll know what's happening to keep your food safely stored at appropriate temperatures.

Some refrigerators with freezers have an automatic defrost feature. This mechanism works by heating the interior refrigerator coils at scheduled intervals, enabling effective cooling. Controlled cooling prevents frost from building up and optimizes the refrigerator and freezer performance, while you don't even have to shut down the appliance to risk your stored goods becoming too warm.

Today's refrigerators have evolved and progressed to ensure that we enjoy food preservation benefits with minimal maintenance. Keep reading as we delve into the intricacies of how auto defrost works, why it is beneficial, and unravel the difference between frost-free, auto, and manual defrost systems.


Defrosting a frozen fridge freezer, How Does Auto Defrost Work on A Fridge Freezer?

How Auto Defrost Works

As suggested by its name, an auto defrost freezer has an automatic defrosting system. Auto defrost freezers are incorporated with evaporating coils positioned at the ceiling and have fans that circulate cold air when the freezer door is shut.

These fans enable even airflow and consistent cooling throughout the freezer. But they shut off as soon as the door is opened to limit the circulation of warm outside air.

The cold air circulated within the freezer has a lower humidity causing ice or condensation that forms to evaporate and settle on the coils. At regular intervals or whenever frost is detected, the evaporating coils heat up. This heat melts and evaporates the frost, thus defrosting the freezer.

During the defrosting cycle, the temperature in the freezer can vary slightly since the cooling coils are heated. The fans' reactivation is delayed after defrosting to prevent the circulation of warm air. It is also possible to minimize temperature variations by keeping the freezer filled with your material and putting a limit on door openings.

Do You Need Auto Defrost on A Fridge?

Ice build up inside a freezer

You might find that auto defrost is both practical and beneficial, for these reasons:

  • These units require less maintenance than a manual defrost freezer since defrosting happens on a regular schedule.

  • An auto defrost freezer will provide a more uniform temperature than a manual defrost freezer since it forces air circulation via the internal fans.

  • Items can be stored inside the freezer during the defrosting process, so you don’t have to expose these to temperature fluctuations upon transfer.

How Often Does A Fridge Auto Defrost?

A freezer filling up with ice and is in need of defrosting

Most modern refrigerators control how often defrost cycles take place automatically. In many cases, a defrosting timer is incorporated into the unit to ensure frost removal happens on schedule regardless of whether it is necessary.

High-tech refrigerators are fitted with sensors that can automatically detect frost accumulation and then switch on the heating coils after powering off the compressor.

The computer program in these appliances is highly advanced; it even records the number of times you open and close the freezer door, which is a contributing factor to frost buildup.

The Auto Defrost Schedule

Refrigerators incorporated with basic automatic defrosting technology will have a timer so the compressor turns off after cooling the fridge and freezer for 8 to 12 hours. The heating coil switches on and remains powered for about 20 to 40 minutes. But the length of time it stays on will depend on the brand, model, and cubic foot capacity of your freezer compartment.

What's the Difference Between Frost-Free and Auto Defrost?

An empty refrigerator with its freezer door left open, Can't Open Freezer Door - What To Do?

The primary difference between a frost-free and auto defrost refrigeration system is how they eliminate excess ice and frost from the cavity. A self-defrosting freezer’s heating elements cycle on and off throughout the day.

During defrosting, water from melting ice is flushed through a tiny hose at the back and lands on a drip tray positioned at the unit’s base. In contrast, you'll have to remove the excess frost and ice from the cavity of a manual defrost freezer.

Auto defrost

Frost-free is a type of cleaning design feature in freezers. Self-defrosts are an auto defrost cycling process that requires no intervention from the user.

It heats coils within the freezer at scheduled intervals to prevent the buildup of frost. Otherwise known as frost-free or auto-defrost, it is a feature many consumers enjoy since it is easy to clean and a time and labor saver.

Maintenance for Auto Defrost

Self-defrosting freezers are becoming more popular compared to manual defrost types because they considerably mitigate freezer maintenance. However, they do have several downsides.

The drip tray is positioned behind the bottom trim plate of an upright freezer. There is no need to empty this water tray in many cases since the water will be evaporating on its own. But you will need to be alert of cracked hoses or misaligned drip trays to keep the self-defrosting system working smoothly.

Manual Defrost

A manual defrost freezer is not incorporated with any automatic heating parts to prevent frost or ice buildup. The owner will have to defrost the freezer coils manually as the frost accumulates. Once the coils are covered by a buildup of frost and ice, restrictions in airflow occur, and the freezer won’t effectively cool items.

Maintenance for Manual Defrost

It is recommended that the freezer must be defrosted once the frost has become ¼ to ½ inch thick. But defrosting a freezer can be time-consuming and tedious since everything done is hands-on.

The process involves:

  • Unplugging the appliance.
  • Removing every item from the freezer.
  • Pulling out massive pieces of frost to speed up the defrosting process.

Manual defrost chest freezers will typically have a drain at the chest bottom to let water out. If you are manually defrosting a chest freezer, you might wonder "At What Temperature Should a Chest Freezer Be?"

If you are manually defrosting your freezer, check out "How to Defrost a Bottom Freezer Drawer" for some helpful tips!


We are now spoiled by the many technological advances in refrigeration. An auto defrost fridge freezer is one of the popular features to look for. An auto defrost feature functions by melting ice and frost within the cavity at a scheduled interval, thus preventing manual defrosting by the owner.

Currently, auto defrosts are developed to such a degree that they rival manual defrosting systems. Although refrigerators with manual defrost have a few benefits, auto defrost with its time, and labor-saving features remain a draw for a majority of consumers.

Nymfa Aranas
Nymfa Aranas
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