Why Is My Dehumidifier Freezing Up And How To Fix It?

The importance of regulating indoor humidity is never overstated, and running a dehumidifier is proven to be an effective way to combat dampness. However, it, like any other household appliance, it can go wrong at some point in your life. 

A common problem with dehumidifiers is that they can freeze up. 

Why is your dehumidifier freezing up? The reason can be the low room temperature, inadequate airflow, or a faulty temperature or humidity sensor.

In this post, I will analyze why these reasons can lead to your humidifier icing up and guide you on how to fix it or should you hire a pro.

Don’t be agitated! Continue reading, and you will be able to solve this problem quickly in many cases.

Why does my humidifier ice up?

Sometimes, when you take out the water bucket, you will notice your dehumidifier is not collecting water. While there are numerous causes, frozen coils are frequently to blame.

Your dehumidifier will freeze for three main reasons. Only compressor dehumidifiers (also known as refrigerant dehumidifiers) use chilled coils to collect water, so this post will concentrate on these models.

Low room temperature

When comparing refrigerant dehumidifiers to desiccant humidifiers, we frequently say that refrigerant dehumidifiers are more susceptible to low temperatures.

The ideal operating temperature for a refrigerant unit is between 70°F and 90°F. falls below 65°F, your device becomes less effective and more prone to icing.

To understand it, you need to know how a dehumidifier works. The air is drawn into the machine by a fan. On the inside, the warmer air will pass through the evaporator (cold coils), and the moisture in the air will be condensed and then flow into the water tank.

While the evaporator is cold, the warm air can transfer some heat to it, preventing the coils from freezing up. 

In other words, when the ambient temperature is too low, the air is not able to release enough heat, causing the balance to break and ice to form on the coils.

Limited airflow

When there is insufficient airflow, there is insufficient heat to warm the coil, causing the dehumidifier to ice up.

The dehumidifier is designed to condense a certain amount of air. When less air goes through, the coil will become too cold, creating a proper condition for ice to form. 

This issue is frequently caused by a clogged air filter and a damaged fan. I will provide the solution later.

Broken humidistat

Most, if not all, dehumidifiers these days have a built-in humidistat. It will shut off and on automatically according to your set temperature. 

When it is faulty, the compressor will keep working at a high level, causing the coil to freeze.

Damaged anti-frost function

Because dehumidifier icing is a common problem, manufacturers have included a de-icer to defrost the unit, and the bi-metal thermostat is the main component of the de-icer.

When it detects that the coil is about to ice up, it will normally turn off the compressor while the fan continues to run.

When it is faulty, the compressor will continue to make the evaporator stay cold even when the water will convert to ice immediately.

How to fix a dehumidifier that is freezing up?

Until now, I believe you have already understood the causes of dehumidifier icing up. This section will discuss how to troubleshoot them one by one.

Increase the room temperature 

increase room temperature

When you see the dehumidifier is icing up, the first step you need to do is to check the thermometer. 

If it is below 65°F, you can turn on your heating equipment or move your dehumidifier to another warmer room. 

Allow the ice in the machine to thaw and turn on the device again to test if it works again. If not, you can try the following solutions.

Clean or replace the air filter 

The air filter sits in front of the cold coils and can filter out pollutants in the air, preventing dust, dirt, and other contaminants from landing on the coil.

Over time, it can accumulate more and more impurities and block the airflow, which is the main reason for freezing. 

To clean the air filter, rinse it under the water with dish soap and let it air dry. If you find the debris is too hard to remove, it is time to replace it with a new one.

Aside from that, if you discover that the coils are dirty. You should also clean it.

Repair the restricted fan blade or blower wheel

The dehumidifier sucks up the air using a fan. If the filter is not blocking the airflow, the culprit may be the fan. 

Sometimes, the fan blades or blower wheels can become stuck due to debris or other factors. You can disassemble the machine and remove the fan cover to manually rotate the blades and wheels to see if anything is impeding their movement.

When the movement is limited, you can clean the blades to see if they are back to normal. If not, you have to replace them.

Fix or replace the fan motor

The fan blades may work smoothly, but it rotates so slowly that the airflow extracted is very weak. 

In this case, you have to take a look at the fan motor. Maybe it hums but can’t let the fan blades spin. Usually, you have to replace it.

I don’t suggest you replace a fan motor on your own since you don’t know which one to buy and the replacing process could be complicated. 

The fan motor could be expensive, and you should also consider the labor cost. More often than not, buying a new dehumidifier could be more sensible.

Test and replace the humidistat or thermostat

If none of the methods can stop your dehumidifier from freezing up, you should check the states of the sensors. 

Rather than fixing it, replacing it is often the way to go. However, it isn’t easy to make the judgment, making calling in a professional necessary. 


This post illustrated why the dehumidifier will freeze up and how to repair a dehumidifier with coils that are icing up.

The dehumidifier needs heat in the air to warm the coil, it can freeze up when the temperature is too low. Reduced airflow is also the cause since the coils are designed to cool more air. The damaged sensors will also affect it as your machine could work excessively.

To fix it, you should clean your humidifier, including the air filter, coils, and fan blades. Keeping your room at a higher temperature is also crucial. If these methods don’t work, you may need to replace some components, like temperature and humidity sensors or fan motors.

About The Author

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested dozens of products in person, like humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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