Why Does My Dehumidifier Keep Freezing Up?

High humidity in your home can be extremely uncomfortable and it can also lead to the growth of mold and mildew. Excess moisture can result in respiratory conditions like allergies and asthma, and damage items and the structure of your home. To reduce humidity and prevent its harmful effects, a dehumidifier is a good investment for homes in humid regions.

You can find a lot of useful resources to do the task of choosing the best dehumidifier for you, but keeping your dehumidifier working properly for a long time will also take some time and effort from you. However, no matter how well you maintain your dehumidifier, some problems may still arise due to natural wear and tear or unavoidable weather conditions.

If you notice frost in your dehumidifier, it may simply be because of low ambient temperatures. Below, we will talk about other possible causes for your dehumidifier freezing up. Then, we’ll give you some troubleshooting tips you can do on your own. Although, if the problem seems serious, it’s always best to consult with your manufacturer’s customer support or contact a licensed HVAC technician to check your dehumidifier.

First, you must understand how your dehumidifier works so you can tell when it’s not functioning properly.

How Your Dehumidifier Works

Dehumidifiers extract moisture from the air using different methods. What most people are familiar with is the compressor or refrigerant dehumidifier. It works similarly to an air conditioner and uses a compressor to move the coolant or refrigerant from the condenser to evaporator coils to cool the air. 

Firstly, a fan draws the humid air into the dehumidifier and passes it over the cold coils. As the temperature decreases, the air loses its ability to hold moisture. Water droplets drip down into the internal tank or out through the drain hose. 

The dryer air is then reheated and exhausted into the room. Due to this process, this type of dehumidifier generally performs well in warm and humid conditions. It can only operate in temperatures as low as 41°F, while its efficiency starts to decrease at 65°F. This is because it cannot cool down the already cold air and the condensate may end up freezing on the cold metal coils instead.

Dehumidifier Freeze

Why Does a Dehumidifier Freeze Up?

Before we talk about the solutions, you will need to root out the cause of your dehumidifier icing up. Once you have an understanding of the problem, you can prevent it from happening again.

1. Low Temperature

Low temperatures are a weakness to refrigerant dehumidifiers. The most commonreason a dehumidifier freezes is because the room is simply too cold. Even if the unit can operate in lower temperatures, when the ambient temperature drops below 65°F, frost may start to form on the coils. Remember that the refrigerant system needs to cool the air. However, if the air is already cold, the water vapor may freeze on the coils instead. Most dehumidifiers have a defrost function to stop the compressor when frost starts to build up. 

2. Blocked Airflow

When auto defrost is activated, the unit stops dehumidifying but the fan continues running to melt the ice. If your unit does not activate auto defrost, the unit may ice up, damaging its coils and other internal components. If the auto defrost is functioning well but the airflow is blocked, the fan may not be able to fully melt the ice. The air inlet or outlet may be blocked if the unit is too close to walls, furniture, or other items.

3. Clogged Air Filter

Before the air enters the unit, it has to pass through the filter to protect the internal components of your dehumidifier. If the air filter is clogged with dust, dirt, and other impurities, it limits air circulation. Limited air flow due to a poorly maintained filter will not be able to melt the ice as needed, resulting in frozen coils. Many dehumidifiers feature indicator lights to remind the user to clean the filter after a certain amount of time.

4. Defective Fan

If the dehumidifier is turned on but you don’t hear a whirring sound from the fan, then you may be dealing with a faulty fan motor or blower wheel. These vital components facilitate air circulation and prevent the coils from icing up. If there are no blockages and the air filter is clean, but there is no airflow, then the fan itself may be broken or simply too dirty that the fan blades cannot spin.

5. Dirty Coils

Dirt and debris can also get on the evaporator and condenser coils, which can disrupt the airflow and cause the dehumidifier to ice up. Any small dust, dirt, or lint that passed through the filter will accumulate inside the unit and settle on internal components including the dehumidifier coils. The coils work to cool the air then reheat it and if they are not in their best condition, it can lead to frost buildup on the coils. That’s why it’s vital to maintain the air filter to protect the coils and help extend the dehumidifier’s life.

8. Other Mechanical or Electrical Failures

Refrigerant leakage, overheated compressor, electronic malfunction, or faulty wirings can lead to ice buildup inside your dehumidifier. If frost develops on the coils, or there’s a buildup of dust and other impurities, then the compressor can become overheated. If you regularly perform proper maintenance and you’ve checked all components but your unit is still not working, then the compressor could be the issue. This can be hard to tell without expert knowledge, so it’s still best to ask your manufacturer or get a professional to check your unit and assess the problem.

How To Fix A Dehumidifier That Is Icing Up

Here are some ways you could troubleshoot a dehumidifier, starting from the easiest steps.

First, check the temperature in the room. When the air temperature drops below 65°F, water vapor may start to freeze on the coils. If your dehumidifier is functioning properly, it should activate auto defrost to melt the frost completely before resuming normal operation. If the unit does not defrost automatically but you notice ice, turn it off and let the ice melt by operating in fan mode or using a separate heating system. 

To avoid frozen coils, try not to run your unit in cold conditions in the first place. Usually, cold weather comes with low humidity anyway. Check the room temperature and humidity to determine if you even need the dehumidifier. Do not operate the dehumidifier below the recommended temperatures. 

After you’ve checked the temperature, make sure there is no blockage on the dehumidifier air circulation. Keep 8 to 12 inches distance away from walls and other objects to allow the dehumidifier to breathe. 

Unplug the dehumidifier and wipe down any dust, dirt, or debris that is blocking the air inlet or outlet. Also, inspect the fan for any loose or damaged parts. Clean the blower wheel or fan blade and remove any buildup. If you hear any unusual sound or the fan is not working even after cleaning and removing blockages, check other components.

Clean the filter regularly to prevent dust, dirt, hair, and other airborne contaminants from entering the unit. The filter is typically located behind the air intake grille of the dehumidifier.  To clean the filter, you can place it under running water or soak it in warm water with soap to remove stubborn dirt particles. You can also use a vacuum cleaner to remove any remaining debris. Let the filter air dry before placing it back into the dehumidifier. For more specific instructions on filter cleaning or replacement, check the owner’s manual.

It’s also important to clean the evaporator and condenser coils periodically to reduce particle accumulation and ice buildup. Clean coils can also protect the compressor and fan motor from burning out. Simply turn off and unplug the dehumidifier, remove the cover, then gently vacuum the coils with a brush attachment. Before you touch the coils, check the manual for guidelines. If you are unsure how to do it, you can leave this to a professional.

Check the humidity or temperature sensor. In some cases, the dehumidifier’s digital screen may display an error code that indicates some type of electrical error. If you’ve already cleaned the dehumidifier and this happens, just restart the unit and check the manual for instructions. If the issue isn’t something you can fix on your own, do not attempt to disassemble and fix it yourself. It’s better to call customer service or a trusted technician to get your dehumidifier checked as soon as possible.

Best Dehumidifiers for Low Temperatures

If you have an extremely cool space that needs dehumidification, we’ve done a lot of research on the best low temperature dehumidifiers. In this article we’ve listed our top picks for humidity control devices that can handle cold evaporator coils or use alternate technology to remove excess humidity.

>> Check out our Best Low Temperature Dehumidifier Picks Here <<


Even dehumidifiers designed for low-temperature operation may start to form frost when temperatures drop to 65°F and below. Compressor dehumidifiers have a built-in auto defrost feature that automatically stops operation to melt the ice. Despite this, for some reason, you may notice ice forming inside your dehumidifier. Be reminded not to operate a dehumidifier when the coils are frosted. If auto defrost isn’t working, turn off and unplug the unit and perform the troubleshooting tips we discussed above. If everything fails, call your manufacturer or a licensed technician to have your unit checked.

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