Most freezers are equipped with features and temperature controls to ensure that the contents stay frozen despite the door opening or warming due to new items being placed inside. Even when these features are working properly, it is possible to find that the back panel of your freezer feels warm for a number of reasons.
When large amounts of warm food are stored in a freezer, it takes a while for the temperature inside to cool enough to begin freezing. Warm food can actually increase the temperature. If you've recently put a large amount of food at the back of the freezer, this may result in warming that seems to localize at the back panel. Allow the freezer four to six hours to stabilize. Once the food begins to freeze, the back panel should no longer be warm. Also examine how you've placed items in your freezer. If the food or containers are blocking the vents, the cool air can't circulate properly and areas of your freezer may warm as a result.
Although most refrigerators and freezers are factory preset to the ideal temperature, occasionally the amount of food in the freezer or the environmental conditions in the room can affect its ability to freeze at that temperature. This can result in warm patches, such as the back part of the freezer. Turn the temperature control for your freezer one setting colder and wait 24 hours for the interior temperature to stabilize.
If the freezer door is opened frequently, or for some reason it is not closing entirely, parts of your freezer may warm as cold air is lost. First check the seal on your door to ensure the freezer is closing properly. Food packaging may be preventing a tight seal or the door itself may be damaged. If this is not the problem, leave the door closed for several hours to allow the interior to cool properly.
Most freezers have an automatic defrost cycle that is operated by a timer. When your freezer goes into defrost mode, it stops cooling. Allow the freezer 30 minutes to finish a defrost cycle and check the back section again. If the warming is a result of the defrost cycle, you should notice the warm area cooling after the cycle is done. If the defrost cycle continues longer than 30 minutes, the timer may be faulty and need repair.
There is a compressor motor typically located at the back of your freezer, near the bottom. Listen to the freezer at this area. If you don't hear a steady noise or humming, there could be a problem with one of the compressor components. Call your manufacturer or appliance repair store to have it inspected and repaired.
If the compressor is running, but the freezer is still warm at the back, your condenser or evaporator coils may be malfunctioning. Now and then evaporator coils may freeze and air cannot pass over them as it needs to. This results in the freezer not cooling as it should. Manually defrost the freezer by moving the contents to another freezer and turn it off for about 24 to 48 hours. Wipe out water as it defrosts with a towel to prevent water damage to your floors. Turn the freezer back on once it is fully defrosted. If the back panel is no longer warm, then the coils were frozen.