The sealed system in the dehumidifier has a compressor that runs the refrigerant through it. If the compressor doesn't work, have a refrigerator service technician replace it; by law, an EPA-licensed technician must complete this repair.
There is a temperature sensor on the coils. The electronic control board can detect excessive frost if the temperature is too low. The electronic control won't defrost the coils if the thermostat isn't working properly. The thermostat should be replaced if it does not detect the temperature.
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