If your freezer is not blowing cold air despite the fridge working fine and you've already checked the seals, cleaned the coils, and replaced the evaporator thermostat, there could be several other potential reasons for this issue. Here are some additional troubleshooting steps to consider:
Defrost Timer or Control Board: The defrost timer or control board in your freezer might be faulty. If it's not working correctly, it can prevent the freezer from cooling properly. The defrost timer controls the defrost cycle, and if it gets stuck in the defrost mode, the freezer won't cool. The control board is responsible for regulating various functions, including the compressor and fans. If it malfunctions, it can disrupt the cooling process.
Condenser Fan Motor: The condenser fan motor helps to dissipate heat from the condenser coils. If the fan motor is not working, the freezer's cooling efficiency will be affected. Check if the fan is spinning freely and replace it if it's faulty.
Evaporator Fan Motor: The evaporator fan motor circulates cold air throughout the freezer. If it's not working, the freezer won't get cold. Listen for the sound of the fan running when you open the freezer door. If you don't hear anything, the fan motor might be faulty and needs replacement.
Compressor Issues: The compressor is the heart of the refrigeration system. If it's not working, the freezer won't cool properly. Check if you can hear the compressor running or vibrating. If the compressor is not functioning, it might require professional repair or replacement.
Refrigerant Leak: A refrigerant leak can lead to a loss of cooling capacity in the freezer. If there's a leak, you might notice frost or ice buildup on the evaporator coils. Repairing refrigerant leaks should be done by a certified technician as handling refrigerants requires specialized equipment and training.
Temperature Control Thermostat: The temperature control thermostat regulates the cooling cycle. If it's defective, it might not signal the compressor and fans to run, leading to a lack of cooling. Test the thermostat for continuity and replace it if necessary.
If you've gone through these troubleshooting steps and are still unable to resolve the issue, it's best to seek professional help from an appliance repair technician. They have the expertise and tools to diagnose and fix complex problems with refrigeration systems.