There are a number of reasons that a refrigerator defrosts but then freezes back up. Some of these problems can be resolved through some basic cleaning and troubleshooting, but other causes will require professional service repair or replacement, such as problems with the refrigerator defrost system or compressor.
One of the primary components in a refrigerator responsible for temperature inaccuracy is the condenser coils. These coils can get dusty or dirty and air flow slows down as a result, causing ice to build up on the evaporator coils or inside the refrigerator or freezer compartment. Cut power to the refrigerator and remove the refrigerator toe grille. Clean the condenser coils with a vacuum cleaner brush attachment or a soft brush, then reattach the toe grille. Finish cleaning the condenser coils on the back of the refrigerator, which are below the fan on the refrigerator rear.
The evaporator coils are located in the freezer section behind a panel. You will know there is a problem if frost starts to build up inside the freezer walls or ceiling. If the evaporator coils are so covered in frost that the fan cannot move air over the coils, cooling is limited and ice can build up even after the defrost mode operates. You can test this by removing all perishable food from the refrigerator and leaving the doors open, placing towels on the ground in front. Turn off the refrigerator and freezer thermostat and wait up to two days for the unit to manually defrost. Wipe up any water that develops and reconnect power, letting the refrigerator cool before adding any food. If the refrigerator no longer freezes up, the ice on the evaporator coils was to blame for the problem.
There are a variety of components in the defrost system that may cause a refrigerator to defrost improperly, resulting in freezing or icing even after the defrost program runs. The defrost thermostat, heater and timer all must work in order for the defrost program to operate correctly and if any one component is failing or is broken, icing may result. Contact the refrigerator manufacturer or a qualified service professional if the defrost system is not running or the frost keeps returning.
Additional problems that may cause freezing include issues with the refrigerator compressor or the refrigerant level. Contact a service professional for further diagnosis and repair if cleaning the refrigerator and performing a manual defrost does not resolve the situation.
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