Why Does Dehumidifier Freeze Up And How To Fix It

On a bitterly cold winter, there are many things that will stop functioning completely. This includes your trusty dehumidifier that may freeze up and fail to work in spite of the anti-defrost feature. So what could possibly cause the dehumidifier coils to ices up? How do I keep my dehumidifier from freezing in the future? Find out the reasons behind the icing up and our best solution to fix it once and for all.


Why Does Dehumidifier Ice Up?

Before we get into the dehumidifier icing up solution, first you will need to find out what causes dehumidifier coils to freeze up especially those that are placed in the basement. Once you have a grip of what’s going on, you will truly understand why is it important to prevent future ice buildup. Ready? Here are the few common causes:

Danby 30 pint Dehumidifier

1. Running Below 65°F Temperature

The most common cause why dehumidifiers freeze up is because the room is simply too cold. Even if the machine can operate at a low temperature, it is typically cap at 65°F degrees. Running below the recommended temperature will cause ice to build up on the condenser coils. The only saving grace is the auto-frost mode feature that will shut down the compressor when the dehumidifier coils become too cold.

2. Faulty Humidity Sensor

A faulty humidity control or humidistat sensor may cause the dehumidifier coils to freeze up and damage the internal components. Similar to a thermostat, a humidistat is part of the electronic control module that monitors the ambient relative humidity level. It is very important as the dehumidifier anti-frost/ auto-deicing mode relies on the sensor signals to shut off the compressor to prevent an ice build-up. The compressor will resume back operation once the ice on the coils has melted.

3. Faulty Bi-metal Thermostat

A faulty bi-metal thermostat may lead to the icing of the coil particularly when the room temperature is low while humidity remains high. This could be due to wiring issues where the electrical contacts that power the compressor circuit is welded shut or a short circuit. Bi-metal thermostat reads and monitors the temperature of the evaporator coil. Without an accurate reading, the compressor will keep running and the de-icing of the coils will not happen.

4. Faulty Fan Motor Or Blower Wheel

If there is no whirring noise coming from the dehumidifier, a defective fan motor or blower wheel could be the blame. Fan motor/ blower wheel is vital component parts that facilitate airflow circulation and prevent the condenser coils from freezing up. A visibly clean air filter is a good sign of a broken fan motor as there is no air flowing through the grille. Additionally, dust, dirt, or debris could also impede the fan from spinning smoothly. This could result in broken or loose fan blades that further restrict the airflow output.

5. Clogged Air Filter

A dirty filter clogged with dust, hair, and dirt can result in a frosted dehumidifier due to restricted air circulation. An air filter is there to trap dust particles in the air and protect the internal components. Alarmingly, most people didn’t realize there is a filter installed in their dehumidifier or didn’t bother to clean it. A poorly maintained filter could limit the airflow that pushes through thus continue to cause issues to the dehumidifier.

6. Dirty Evaporator/ Condenser Coils

Dirty deposits on the evaporator and condenser coils can cause a dehumidifier to ice up because the air cannot circulate properly. Over time, dust, dirt, hair, lint that bypassed the filter will accumulate and occupy the coils space. That’s why the washable air filter plays a key role in protecting the coils from airborne particles and extending the dehumidifier’s life expectancy.

7. Disruptive airflow

Air inlet or outlet blockage could also restrict airflow circulation and causes the dehumidifier to ice up. This usually happens when a dehumidifier is placed too close to the wall or there are foreign objects obstructing the ventilation.

8. Other Mechanical or Electrical Failures

Refrigerant leakage, burn compressor, electronic control malfunction, faulty wiring, and even a broken switch could lead to an impending ice build-up. Remember, a single faulty part in the dehumidifier’s refrigeration system could disrupt the whole operation.

How To Fix A Dehumidifier That Is Icing Up

Stuck with a frozen dehumidifier that can’t get it to restart? Here are several ways you could troubleshoot a dehumidifier before sending it to the service center.

  • Check the room temperature with a thermostat or thermometer. Do not operate the dehumidifier below the recommended temperatures of 65 °F degrees. That said, there are exception models e.g. from Frigidaire, Soleus that can run even in colder temperatures. Ideal for basement use without having to worry the dehumidifier will ice up.
  • Make sure there is no blockage on the dehumidifier air ventilation. Educate your children not to insert foreign objects or cover the air inlet or outlet with clothes. Keep 1-2 feet distance between walls to ensure optimal airflow distribution.
  • Clean the filter regularly to prevent dust, pet hair, and other airborne contaminants from making its way to the coils. The filter is typically located behind the grille of a dehumidifier. Lightly vacuuming the surface of the filter to remove the trapped particles without damaging it. Most filters also can be soaked and washed in warm water to remove stubborn dirt particles. Let the filter room dry before placing it back in the compartment. Check the instructional manual for a clearer picture of how to care for the filter.
  • Unplug the dehumidifier and clean any dust, dirt, or debris that is blocking the fan from rotating freely. While you’re at it, carefully inspect the fan blades for loose or damaged parts. If there is still a weird humming sound or the fan is not spinning even after removing the blockage, send it to the service center for repair.
  • When the digital screen is displaying an error code that points to an electrical error, try restarting the dehumidifier or gently clean the sensor with a cotton swab. If you have a multimeter, you can inspect the humidistat or bi-metal thermostat status by listening to the clicking signals with open circuit contacts. If is not working, send it back to the service center for repair. Do not attempt to disassemble and fix it yourself without prior knowledge.
  • Clean the dehumidifier coil fins periodically to reduce particle obstruction and ice formulation. It is recommended by few manufacturers to do so as it can protect the compressor and fan motor from burning out. Simply unplug and turn off the dehumidifier, remove the chassis cover, and gently vacuum the coils with a brush attachment. Take your own sweet time in cleaning as the coils are fragile and can be easily bending when applied force. If you are unsure how the coil cleaning can be done for a particular model, check the manual for a clearer set of instructions.
  • Never operate a dehumidifier when the coils are frosted. Unplug from the power source and allow the ice to melt completely before attempt to restart the dehumidifier. When possible, elevate the dehumidifier on higher ground to make use of the warmer temperature. Make sure the dehumidifier is placed on a flat surface to avoid spillage. Empty the water tank regularly to prevent the dehumidifier auto-shutoff from activation.
  • If the dehumidifier is spotless, running smoothly, yet icing still occurs, it is likely due to mechanical failure or electrical faults. Your only option is to send it to the service center with qualified technicians for inspection and repair.

What Is A Refrigerant Dehumidifier?

Refrigerant dehumidifiers are highly effective machines that reduce indoor humidity. Each model comes with key components such as evaporator coils, condenser coils, a fan motor, a reservoir, and a built-in humidistat. The dehumidifier begins by pulling damp air into the ventilation and passes to the evaporator coils for condensation. Water droplets will be drained out and stored in the reservoir or pump straight out via a hose. Dry air will then passes to the hot condenser coils and release out as mist to complete the cycle.

Side Effects Of A Frosted Dehumidifier

  • Reduce life usage expectancy due to damaged parts.
  • Fan motor and compressor will have to work harder to absorb the excess moisture.
  • More rattling noise or vibration as wear and tear parts are under constant stress.
  • Dip in dehumidification output with more blockage in the coils.
  • A surge in electricity bills as the operational hours will be longer with dropped performances.
  • Fire hazard risk on continuous use.



Max Fernandez

A loving father and a dedicated reviewer for airfuji.com with more than 1000 air purifiers under his belt. Max Fernandez is also one of the million patients currently suffering from asthma. Feel free to nudge him if you have any questions.