How to Repair a Dehumidifier with Coils That are Icing Up

If your dehumidifier coils are freezing up and the room temperature is above 65 degrees Fahrenheit, there may be an issue with the humidity control. This control, also known as a humidistat, functions similarly to a thermostat to monitor the relative humidity level in the room. The humidistat electrical contacts power the compressor circuit to cycle on. If the humidistat is not reading the humidity correctly, the compressor will stay on which can cause the coils to freeze up. The electrical contacts can also become welded shut, leading to the same problem. To troubleshoot the humidistat, first disconnect power to the unit. Turn the humidistat dial and listen for the click that signals it is working properly. You can also test the control for continuity using a multi-meter. Keep in mind that as you rotate the control, the contacts should be open circuit, if not, it will need to be replaced.

If your dehumidifier coils are freezing up and the room temperature is above 65 degrees Fahrenheit, there may be an issue with the blower wheel or fan blade. These two parts facilitate the air flow which is necessary for a dehumidifier to keep the condenser coils from freezing up. If the air filter is clean and there is no air flowing through the grille, remove the fan cover to visually inspect the coils. Remove any dirt or debris that could be impeding air flow. Check the blower wheel and fan blade to make sure nothing is blocking their movements. Take this opportunity to clean these parts, or replace them if they appear to be damaged. Manually rotate the fan motor to ensure it will move freely before restarting the unit.

If your dehumidifier coils are freezing up and the surrounding temperature is over 65 degrees Fahrenheit, the fan motor may be the issue. This dehumidifier part facilitates the air flow necessary to keep the condenser coils from freezing up. To troubleshoot the dehumidifier fan motor, check to see if air is flowing from the grille, and that the air filter is clean of dirt and debris. Remove the fan cover and check for any signs of damage to the coils or fan. Take this opportunity to clean any parts that are dirty, and check to make sure the fan motor is able to rotate freely, with no objects blocking its way. Turn the unit to fan mode, and observe how the fan operates. Be very careful when performing this repair. If the fan hums but does not spin, or spins slowly, it will need to be replaced. If the fan neither hums nor spins, it should be tested by a qualified person, using a multi-meter.

If your dehumidifier condenser coils are freezing up even though the temperature is above 65 degrees Fahrenheit, there may be an issue with the bi-metal thermostat. This part is included in certain dehumidifier models to keep the evaporator coils free of ice, particularly during periods of high humidity or low temperatures. The thermostat works by monitoring the temperature of the evaporator and causing the fan only to run, with the compressor stopped, to de-ice the coils. When the thermostat is faulty, it may not read the temperature correctly meaning the compressor will continue to run and the coils with freeze up. To troubleshoot this part, check to see if the bi-metal thermostat is making positive contact with the evaporator coil, if so, it means it is not working and needs to be replaced.

If your dehumidifier condenser coils are freezing up even though the room temperature is above 65 degrees Fahrenheit, there may be a problem with the humidity sensor, also known as the temperature sensor. This dehumidifier part is common on electronic control models. It monitors the ambient relative humidity, and in some cases, the temperature of the evaporator coil. It is important that the sensor reads the room temperature accurately, to signal the compressor to shut off to keep the coils from icing over. To troubleshoot this problem, first make sure that the sensor(s) are aligned correctly with the control board. Check the electronic control for a fault code which signals the sensor is faulty.