Why is My Dehumidifier Freezing Up?

By Mark J. Donovan

A dehumidifier contains heating and cooling coils and fins. Warm moist air, such as in a basement is drawn over these coils and fins by a fan that is in the dehumidifier. As the warm air is drawn over the coils the water vapor condenses and collects on the cooling coils and fins. The condensed water vapor then drips off of the cooling coils and fins, and into either a drain pan or a drip hose that flows into a sink, bucket or sump pump well.

During the process of condensing the water vapor, the water vapor normally produces enough heat to prevent the cooling coils from freezing up. However when there is a lack of humidity in the room or the temperature is too cool in the room, there is the potential for the dehumidifier to freeze up. The threat is exacerbated if the cooling coils are covered in dirt and dust.

To prevent the dehumidifier from freezing up there a few things you can do. First, if the humidity is low then turn off the dehumidifier. Alternatively you can cycle the dehumidifier off and on every few hours. This will allow the cooling coils to warm up and melt any ice that could be forming on them. Second, you can raise the temperature in the room to lower the risk of ice formation in the dehumidifier. Third, make sure the cooling coils and fins are free of dirt and dust. Finally, make sure the dehumidifier is up off the floor of the basement or room. Warm moist air rises and cool dry air falls. By raising the dehumidifier up off the floor the dehumidifier will work more efficiently and it will have less chance of freezing up.