How to Deal With Frost Buildup in Your Freezer

Quick answer

Freezer frost buildup usually happens when warm, humid air gets inside, through a door left ajar, a worn door seal or frequent opening. On a manual-defrost freezer, some frost is normal and you remove it by defrosting from time to time. On a frost-free freezer, a thick layer of ice on the back wall can point to a defrost system problem that needs a qualified technician. This guide helps you tell the difference and handle the safe parts yourself.

Safety first

• Unplug the freezer before defrosting. If you can’t reach the plug safely, switch off its circuit breaker.
• Never use knives, ice picks or screwdrivers to chip ice. You can puncture the tubing or walls that carry the cooling gas, which is a repair only a qualified technician can attempt.
• Don’t use a hair dryer, heat gun or space heater inside or near the freezer. Melting water and electrical devices are a shock risk, and heat can warp plastic liners.
• Keep melt water away from the outlet and cord. Lay towels down and empty trays often.
• Stop and call for help if you see sparks, smell burning, or water reaches the outlet.

Before you begin

First, figure out which kind of freezer you have. Your owner’s manual will say whether it is “manual defrost” (common in chest freezers and some small uprights) or “frost-free” (also called automatic defrost). If you don’t have the manual, find your model number and manual using the rating label.

Next, note where the frost is. A thin, even layer on the walls of a manual-defrost freezer is normal over time. Frost around the door opening points to a sealing problem. Thick ice on the back wall of a frost-free freezer, or frost on food packages in one area, deserves a closer look.

Finally, plan for your food. Defrosting can take several hours, so have coolers and ice packs ready before you start.

Possible causes

Things you can check yourself:

• The door was left slightly open, or something on a shelf is stopping it from closing.
• The door gasket (the rubber seal around the door) is dirty, folded or torn.
• The freezer is opened often or for long periods, especially in a humid room.
• Warm or uncovered food was put inside, adding moisture.
• The freezer isn’t level, so the door doesn’t swing fully closed.
• Packages are blocking the air vents inside a frost-free freezer.
• A manual-defrost freezer simply hasn’t been defrosted in a while.

Problems that need a technician:

• The automatic defrost system in a frost-free freezer has failed, so ice keeps building on the back wall.
• A defrost drain blocked behind a panel, causing ice in the bottom of the freezer.
• A faulty fan or temperature control.
• A problem with the sealed cooling system.

Reducing frost and defrosting safely

1. Check that the door closes completely. Rearrange anything sticking out from the shelves or door bins. Open and close the door a few times and watch the seal meet the cabinet. Does it close firmly every time? If not, look at leveling in step 3.
2. Clean and test the door seal. Wipe the gasket with warm, soapy water and dry it. Close the door on a sheet of paper at several points around the door; it should grip. Does a section let the paper slide out? A worn or torn gasket may need replacing. Check your manual or manufacturer support for the right part.
3. Check the level. Many uprights are meant to tilt slightly back so the door swings shut. Adjust the front leveling feet only as your manual describes.
4. Keep the vents clear and limit openings. In frost-free models, don’t stack packages against the vents. Let hot food cool before freezing it, cover containers, and decide what you want before opening the door. Is new frost forming more slowly after a week or two? If yes, the cause was likely humid air getting in.
5. Defrost a manual-defrost freezer. Unplug it and move the food to coolers. Leave the door open, put towels around the base, and place a shallow pan where water collects. Some chest freezers have a drain plug; use it only as your manual describes. You can place pans of warm (not boiling) water inside to speed things up, and gently lift away loosened ice with a plastic scraper. Is all the ice gone? Wipe the interior dry, plug the freezer back in, and wait until it’s cold before reloading food.
6. Watch a frost-free freezer after cleaning. If you defrost a frost-free freezer to clear thick ice and the same heavy ice returns on the back wall within days or weeks, the automatic defrost is likely not working. Did it return? Stop here and contact a technician.

If your freezer section is also making the fridge warm, see refrigerator not cooling. If melt water soaked the floor or cabinets, dry them quickly to help prevent mold.

When to stop and call a qualified technician

Contact a qualified appliance technician or the manufacturer’s service network if:

• A frost-free freezer keeps building thick ice on its back wall, or the fridge section warms up as ice grows.
• You see ice forming on the floor of the freezer or water leaking from underneath, which can mean a blocked drain behind a panel.
• The fan sounds like it’s scraping ice, or you hear no fan at all.
• An error code appears and stays after you follow the manual. Look up the code in your owner’s manual or on the manufacturer’s support site; codes vary by brand and model.
• You accidentally punctured the interior wall or tubing while removing ice. Unplug the freezer, ventilate the room, and don’t try to seal it yourself.
• The breaker trips, or you smell burning.

Regular checks of seals and coils are part of a good routine; see the appliance maintenance checklist for ideas.

FAQ

How often should I defrost a manual-defrost freezer?

There’s no single schedule for every model, so follow your owner’s manual. A common rule of thumb is to defrost when the frost becomes thick enough that it covers shelves or makes the door hard to close. Thinner frost is easier and faster to remove.

Why does my frost-free freezer have ice on the back wall?

Frost-free freezers melt frost on a timer. When that defrost system stops working, ice builds up on the back wall, often over the cooling coils. Defrosting can clear it temporarily, but a technician needs to check the defrost parts if it keeps coming back.

Can I use a hair dryer to defrost faster?

It’s not recommended. Using an electrical device around melting water creates a shock risk, and the heat can warp plastic parts. Pans of warm water and patience are the safer option.

Is frost on food packages a sign of a problem?

Small ice crystals on food can come from moisture inside the food or from air getting in. If it gets worse quickly, check the door seal and how often the freezer is opened. Wrapping food tightly also helps.

Do I need to empty the freezer to defrost it?

Yes. Move food into coolers with ice packs while the freezer is unplugged. Reload it only once the freezer has cooled back down, which can take a few hours.