Condenser Coils are Dirty
If the condenser coils are located within the freezer walls, the coils do not require cleaning. However, if the condenser coils can be readily accessed from behind or under the unit, you should clean them every 6-12 months. If the condenser coils are dirty, they won’t be able to dissipate heat effectively, greatly reducing the cooling capacity of the freezer. If the condenser coils are dirty or have not been cleaned in a while, clean them.