If your freezer is not blowing cold air despite having checked and addressed common issues like seals, clean coils, and replacing the evaporator thermostat, there could be several other possible reasons for the problem. Here are some additional factors to consider:
Faulty Condenser Fan: The condenser fan is responsible for dissipating heat from the refrigerator's coils. If the condenser fan is not working correctly, it can lead to inadequate cooling in the freezer. Check if the fan is running when the compressor is on. If it's not spinning, the condenser fan motor might be faulty and need replacement.
Defective Evaporator Fan: The evaporator fan is responsible for circulating cold air throughout the freezer. If the fan isn't working, the freezer won't cool properly. Check if the fan is running when the freezer is turned on. If it's not running, the evaporator fan motor might be faulty and require replacement.
Frost Buildup on the Evaporator Coils: Even if the coils are clean, frost can build up on the evaporator coils over time, blocking the airflow and preventing proper cooling. If you notice excessive frost or ice on the coils, it could indicate a problem with the defrost system. The defrost heater, defrost thermostat, or defrost timer may be faulty and need replacement.
Low Refrigerant Level: A low refrigerant level can hamper the cooling process in the freezer. This can be caused by a refrigerant leak, which will require professional attention from a certified technician to diagnose and fix the issue. Refrigerant handling should always be done by trained professionals due to its environmental impact.
Defective Compressor: The compressor is the heart of the refrigeration system. If it's not working correctly, the freezer won't cool effectively. Listen for any unusual noises coming from the compressor, as strange sounds could indicate a problem. A malfunctioning compressor usually requires professional repair or replacement.
Electronic Control Board Issues: Modern refrigerators often have electronic control boards that regulate various functions, including the cooling system. If the control board is malfunctioning or has a defective component, it may not send the proper signals to the cooling components, leading to cooling problems.
Since you've already ruled out some common causes, it's advisable to seek the help of a professional appliance technician to diagnose and resolve the issue. They have the expertise and tools to pinpoint the exact problem and make the necessary repairs to get your freezer back to proper cooling performance.