An issue with the evaporator coils is the most typical cause of a refrigerator not cooling. Evaporator coils can become coated in ice over time, preventing them from performing correctly. If the coils are coated with ice, the ice must be defrosted to resolve the issue. To expedite the defrosting process, use a hairdryer. However, the hairdryer should be set to a low heat setting since excessive heat might shatter an evaporator coil or melt plastic components in the freezer compartment.