How to Defrost a Freezer—Plus Why and How Often

Why Defrosting a Freezer Matters

Freezers work hard to keep your food frozen at a consistent temperature. However, frost buildup can interfere with cooling, causing your freezer to work overtime.

To understand why defrosting a freezer matters, let’s start with an explanation of what causes frost in a freezer.

What Causes Frost in a Freezer

Frost inside a freezer is caused by warm, moist air entering the freezer compartment. The water vapor condenses and freezes on the cold surfaces inside the freezer to create snowy frost.

The sources of warm, moist air entering the freezer include:

• Frequent freezer lid or door openings and leaving the lid or door open for too long while you peruse freezer contents and select the item(s) you need.
• Damage freezer lid or door seal.
• Adding hot food into the freezer.
• Not sealing food packages properly.

What Happens When Frost Accumulates in Your Freezer

When frost builds up on the walls and shelves of your freezer, it can:

• Reduce efficiency: Frost creates an insulating layer, forcing the freezer to consume more energy to maintain the set temperature.
• Waste space: Heavy ice and frost buildup can reduce the usable capacity inside the freezer.
• Shorten lifespan: An overworked freezer experiences more wear and tear, potentially leading to costly repairs or replacement.
• Block the freezer lid or door from closing properly: Excess frost can prevent the freezer lid or door from closing properly—allowing air to enter the freezer and cause freezer burn.

By defrosting your freezer regularly, you help maintain its performance, optimize storage space, and extend its life. Also, a stable environment in your freezer, achieved by removing ice buildup, helps reduce freezer burn and improves the quality and safety of your frozen foods.

What’s the Difference between an Automatic and Manual Defrost Freezer?

Finally, knowing why defrosting a freezer matters requires an understanding of the difference between an upright freezer with an automatic defrost system and a chest or upright freezer that requires manual defrosting.

How an Upright Freezer with an Automatic Defrost System Works

An upright freezer with an automatic defrost system has an evaporator with cooling fins and a fan positioned behind the back all inside the freezer. The evaporator fan blows air across the evaporator fins and then throughout the freezer to cool the compartment and freeze the food.

Every 8 hours or so, the freezer will enter the automatic defrost mode. Here’s how the automatic defrost system works:

1. The compressor and evaporator fan shut off to stop cooling the freezer.
2. A defrost heating element under the evaporator turns on to melt frost and ice off the evaporator fins.
3. The water that melts off the evaporator fins drips down into a pan below the evaporator and then drains down to a collection pan next to the compressor at the bottom of the freezer.
4. When the defrost procedure ends (typically after 30 to 45 minutes), the compressor and evaporator fan restart to resume freezer cooling.

How Chest Freezers and Manual Defrost Upright Freezers Work

Chest freezers and manual defrost upright freezers don’t use an evaporator with fins and an evaporator fan to cool the freezer compartment and freeze items inside the freezer.

The evaporator inside the chest freezer is refrigerant tubing that runs through the inside walls of the freezer just inside the freezer compartment liner.

In a manual defrost upright freezer, the evaporator coils are also located behind the inner walls of the freezer compartment and many upright freezers run evaporator cooling lines through freezer shelves as well. Essentially, the shelves and wall act as the evaporator surface, causing frost to build up on the shelf surfaces and walls as the cold air circulates around them.

Because of the design of the cooling system in chest freezers and manual-defrost upright freezers, there is no central evaporator cooling system that can be heated and defrosted so you have to defrost the walls and shelves yourself in these types of freezers.

How Often Should You Defrost Your Freezer?

Chest freezers and manual-defrost upright freezers typically require defrosting about once a year or when frost buildup exceeds a quarter of an inch.

When you keep your freezer in the garage or a similar area that isn’t climate-controlled (air conditioned), then warm moist air will cause lots of frost to build up as you open the lid or door. Also, if you open the freezer door or lid frequently (once or twice daily), frost will also build up quickly.

You may need to defrost the freezer twice a year or more as if you open the freezer frequently or you have the freezer in the garage or similar area.

Step-by-Step Guide to Defrosting a Freezer

To avoid having to store lots of food, let your food supply dwindle if possible for a week or two before defrosting.

Follow these steps to defrost your freezer:

Store Your Food

Start by moving the frozen food to ice chests to keep it cold and then unplug the freezer.

Prepare the External Drain

Follow these steps to deal with water that will drain out of the freezer during the defrost process:

1. Locate the exterior defrost drain plug and remove it.
2. Place a shallow drain pan under the exterior drain plug or connect a ½-inch drain tube to the drain. You can also use a ½-inch garden hose adapter to connect a garden hose to freezer drain. Route the drain tube or garden hose to a floor drain or the outside of your home.

If you use a drain pan to collect water, you’ll need to monitor the water level in the pan and empty it during the defrost process to prevent it from overflowing.

Remove the Internal Defrost Drain Plug

Pull out the internal defrost drain plug from the bottom of the freezer compartment so water will drain out of the cabinet during defrosting.

Defrost the Freezer

• Leave the freezer lid open and allow frost to melt off the freezer walls and floor.
• To speed up the defrost process, use a spray bottle to spray water on the frost so it melts faster.
• As the ice and frost softens, use a plastic scraper to gently remove chunks of frost and ice. Avoid metal tools, which can damage the interior.
• When all of the frost is melted off and removed from the walls and floor of the freezer, wipe out remaining water on the freezer floor with dry towels.
• Reinstall the interior defrost drain plug.
• Wipe down the interior of the freezer with a solution of warm water and mild detergent.
• Wipe down the interior surfaces with plain water to remove detergent residue.
• Dry the freezer interior completely to prevent new ice from forming quickly.
• Remove the drain pan or drain hose from the exterior drain and reinstall the exterior drain plug.

Restock and Restart the Freezer

Plug the freezer back in and make sure it starts cooling.

Restock the food and monitor the freezer to make sure that it maintains the right temperature.

If the freezer doesn’t cool properly, schedule freezer repair service and we’ll send a technician to your home to fix the problem.

Freezer Maintenance and Usage Tips

A little regular maintenance goes a long way in extending the life of your freezer, minimizing frost buildup and keeping your freezer operating efficiently. Follow these simple maintenance and usage practices to help keep your freezer in top shape:

Check the Freezer Lid or Door Seal

A damaged or loose door or lid gasket seals allows warm air to enter the freezer, leading to excessive frost. Inspect the seal regularly and replace it if necessary.

Here’s a DIY video that shows how to replace the door seal on a refrigerator that has the same type of door seal gasket as many upright freezers:

If your freezer has a bad door seal or lid seal and you need to have a technician replace it, schedule freezer repair and we’ll install a new one for you.

Properly Load the Freezer

Keep the freezer 70% to 85% full. Too much stuff in there will limit air circulation within the appliance — and too little will cause all the cold air to spill out of the freezer every time you open the door or lid.

Keep things evenly dispersed near the middle of the shelves arrange items with space between them to keep from interfering with proper air circulation inside the freezer compartment.

Cool Food Before Freezing

Warm food releases moisture, contributing to frost formation. Let leftovers cool to room temperature before storing them in the freezer.

Limit Door or Lid Openings

Every time you open the door or lid, warm, moist air enters the freezer compartment. Plan your freezer visits to minimize how often and how long the door stays open.

Use bins or baskets to group similar items together. This makes it easier to find what you need and reduces how long the lid stays open.

Use Freezer-Safe Containers

Properly sealed containers reduce moisture and prevent frost from forming on your food.

Clean Condenser Coils

Although you’ll rarely see condenser coils on a chest freezer, some upright freezers do have condenser coils on the back of the unit or underneath the freezer.

Dirty coils won’t cool down refrigerant before it enters the evaporator, resulting in poor cooling performance. Clean the condenser coils when they’re coated with lint and dust (typically twice per year).

Monitor Frost Levels

Even frost-free models can experience occasional buildup. Check your freezer every few months and address frost promptly to prevent larger issues.

Schedule Professional Maintenance

Annual professional freezer maintenance will keep your freezer in top shape and running smoothly. Our technician will visit your home and check all parts of your freezer including the wiring, condenser coils, lid or door gasket and the cold control thermostat or electronic control.

The tech will recommend any repairs needed and make adjustments necessary to keep your freezer operating efficiently and safely.

Professional freezer maintenance is especially beneficial if you’re storing a large amount of meat or produce in your freezer that you can’t afford to lose because of an unexpected freezer failure.

By staying proactive with maintenance and organization, you’ll keep your freezer running smoothly for years to come.

Final Thoughts

Defrosting your freezer might not top your list of favorite chores, but it’s a small effort that pays off with energy savings and better performance.

If it’s been a while since your last defrost session, now’s the perfect time to give your freezer some attention.

Frequently Asked Questions

How do I defrost a freezer quickly?

To quickly defrost a freezer, unplug the power cord, safely store food, remove the drain plugs and prepare to catch or dispose of defrost water. Use a spray bottle to squirt warm water on frost and ice buildup. You can also use a hair dryer or heat gun on a low heat setting to melt ice and frost quickly. Take care not to overheat the freezer compartment liner if it’s plastic. Remove chunks for frost and ice as they loosen from walls and shelves. Drain all water and wipe out the inside of the freezer then plug the power cord back in, restart the freezer and reload the food.

Where is the defrost drain on a freezer?

The defrost drain inside the freezer is located on the bottom floor of the freezer compartment liner. The outlet of that defrost drain will be at the bottom of the outer cabinet. You’ll see plugs covering these openings. For the exact location of the defrost drain in your model, refer to the user guide for your freezer.

Can I defrost a freezer without turning it off?

No. You’ll need to turn off the freezer and unplug the power cord before defrosting the unit. If you leave the freezer on, the compressor and sealed system will continue to cool the freezer and you won’t be able to melt frost and ice off the walls and shelves.

Where does the water go when you defrost a freezer?

When you defrost a manual-defrost upright freezer or a chest freezer, the water goes through the defrost drain and out of the cabinet. Set up a container to catch the water or use a hose or tube to carry away the water from the defrost process. If you have an automatic defrost freezer, the water melted by the defrost heater drips into a tray below the evaporator fins and then drains into a collection pan next to the compressor in the bottom of the freezer where the water evaporates due to the heat produced by the compressor in that area.