What Causes a Frost-Free Deep Freezer to Frost Up?

Bad Seals

• If air gets into your deep freezer, it can cause it to frost up. Check the rubber seals to see if there are areas that seem colder than others. The freezer may also have a poor seal if it is too full and can't fully close. This problem can worsen when it's particularly hot and humid in the room with the freezer, such as during the summer or when you're frequently opening and closing the door.

Blocked Airways

• The deep freezer's self-defrost feature works by alternately blowing hot air to melt any frost and cool air to keep the food at the right temperature. This air comes out of small vents, usually in the back or top of the freezer. Check the owner's manual for your deep freezer model to determine exactly where the vents are and avoid placing food items directly in front of them, which can block airflow.

Self-Defrost Malfunction

• The self-defrosting mechanism is made up of a timer, a thermometer and a heater. If one of these components is not functioning properly, the frost in the freezer that occurs naturally will start to build up. If just one of the components breaks, you can replace only that component.

Blocked Drains

• As the frost in the freezer melts, it needs to drain out. The drain is typically in the back on the bottom of the freezer. The drain can become blocked by a large food item or a piece of debris that went down the drain; the melted frost has nowhere to go and begins to build up. The fix may be as simple as removing a large item from the opening of the drain. If you don't immediately see the blockage, you'll have to remove all the items in the freezer and allow your freezer to completely defrost. This will melt any buildup in the drain and hopefully allow any particles to pass through. If this doesn't work, call an authorized repair technician.