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Dehumidifier Freezing Up – What is Means?

Dehumidifiers, devices designed to extract excess moisture from the air, can be indispensable tools in managing indoor humidity levels. However, in certain circumstances, these appliances may encounter a phenomenon known as “freezing up,” which occurs when the moisture collected by the dehumidifier freezes inside the unit, impeding its function.

This issue can arise from various factors, such as low ambient temperatures, inadequate airflow, or malfunctioning components. To prevent this problem and ensure optimal performance, it is crucial to understand the underlying mechanisms of freezing up and implement appropriate strategies to address it.

How Does a Dehumidifier Work?

dehumidifiersA dehumidifier operates on the principle of thermodynamics, leveraging the properties of condensation and evaporation to reduce the humidity levels in a given space. The device contains a compressor, a condenser, an evaporator, and a fan, all working in tandem to extract moisture from the air.

As the ambient air is drawn into the dehumidifier, it passes over a cold evaporator coil, where the temperature difference causes the moisture to condense into liquid water droplets. These droplets are collected in a reservoir or drained away through a hose. Meanwhile, the dry air is reheated by the condenser and released back into the room, creating a moisture removal cycle.

This process is regulated by a humidistat, which monitors the humidity levels and adjusts the dehumidifier’s operation accordingly. A dehumidifier can help prevent mold growth, musty odors, and structural damage by maintaining a balanced moisture level.

What are the Reasons for Freezing a Dehumidifier?

1. The Room Temperature is Too Low

A dehumidifier’s function relies on the interplay between temperature and humidity, and a low ambient temperature can create conditions that lead to the freezing of the unit.

When the temperature inside the dehumidifier drops below the dew point of the collected moisture, the water vapor condenses and freezes on the evaporator coil, causing ice buildup that obstructs the airflow and compromises the device’s effectiveness. This phenomenon, known as “frosting” or “icing up,” can occur when the temperature in the room falls below the recommended operating range of the dehumidifier, typically between 60-80°F (15-27°C).

In addition, factors such as poor insulation, inadequate ventilation, and high humidity levels can exacerbate the problem and cause the dehumidifier to freeze up more quickly. To prevent this issue, it is crucial to maintain a suitable temperature range and ensure proper air circulation and insulation in the room where the dehumidifier is used.

2. The Fan Motor is Faulty

A faulty fan motor can cause a dehumidifier to freeze due to airflow disruption within the unit. The fan is responsible for circulating air across the evaporator coil, which is necessary for condensation.

If the fan motor is not functioning correctly, the air may not flow through the dehumidifier sufficiently, leading to ice buildup on the coil. This can further obstruct the airflow, exacerbating the issue and causing the dehumidifier to lose effectiveness.

Additionally, a malfunctioning fan motor may increase heat buildup within the unit, further contributing to the freezing problem. To prevent this from happening, it is essential to regularly inspect and maintain the fan motor, ensuring that it is functioning correctly and replacing it promptly if any issues are detected.

3. Faulty Humidity

Humidity sensors or humidistats are essential components of a dehumidifier that regulate its operation based on ambient moisture levels. When the humidity level in the room exceeds the set threshold, the dehumidifier turns on and starts to extract moisture from the air.

However, if the humidity sensor malfunctions or provides inaccurate readings, it can cause the dehumidifier to operate incorrectly. For example, if the sensor fails to detect the correct humidity level, the dehumidifier may continue running even when the air’s moisture content is low. This can lead to the evaporator coil becoming too cold, causing the moisture collected to freeze and obstruct the airflow.

As a result, the dehumidifier can “freeze up,” reducing its effectiveness and potentially damaging its components. Ensuring that the humidity sensor is functioning correctly and calibrated regularly is essential to avoid this issue.

4. Dirty Filters Restricting Airflow

Dirty filters can impede the proper airflow in a dehumidifier, leading to a reduction in heat transfer efficiency and an accumulation of frost on the evaporator coil.

As the air is drawn through the clogged filter, it becomes more difficult to pass over the evaporator, resulting in a lower temperature and an increased likelihood of freezing. The buildup of ice on the coil further restricts the airflow, causing the compressor to work harder and potentially leading to overheating or component failure.

To prevent this issue, it is essential to regularly clean or replace the filters and ensure that the dehumidifier is operating in a well-ventilated area with unobstructed air circulation. Proper maintenance and upkeep of the filters ensure optimal airflow and prevent the freezing up of the dehumidifier.

5. Check The Temperature

Temperature plays a crucial role in freezing up a dehumidifier, as it can directly affect the operation of its internal components. When the ambient air temperature falls below a certain threshold, typically around 65 degrees Fahrenheit or lower, the evaporator coil can become too cold, causing the moisture extracted from the air to freeze on its surface.

This ice buildup can impede the airflow, reduce the dehumidifier’s efficiency, and potentially damage its compressor or other parts. Moreover, low temperatures can also lead to frost or ice forming outside the dehumidifier, further hindering its function and posing a safety hazard.

To mitigate the impact of temperature on a dehumidifier, it is essential to ensure that the device is placed in an area with adequate warmth and ventilation and that its settings are adjusted according to the ambient conditions.

6. Fan is Broken

The malfunctioning of a fan can trigger a chain reaction of issues that may lead to the freezing of a dehumidifier. A fan plays a critical role in dehumidification by circulating air over the evaporator coil and ensuring that the moisture-laden air comes into contact with the cold surface.

When the fan is broken, the airflow is disrupted, reducing the air passing over the evaporator. As a result, the evaporator becomes excessively cold, and the condensation may freeze onto the coil. This ice buildup can eventually spread to other dehumidifier components, such as the condenser, causing further damage and impairing the device’s performance.

7. The frost Detection Sensor is Not Working

The frost detection sensor plays a crucial role in adequately functioning a dehumidifier, particularly in preventing freezing up of the unit. The sensor detects when the evaporator coil temperature drops below a certain threshold, indicating that frost formation is likely to occur.

Once triggered, the sensor sends a signal to the unit to temporarily halt the cooling process and allow the coil to defrost. However, suppose the frost detection sensor is faulty or malfunctioning. In that case, it may fail to detect frost formation on the evaporator coil, leading to an accumulation of ice that can obstruct the airflow and impair the dehumidifier’s performance.

This can ultimately result in the freezing up of the unit and potentially cause damage to the internal components. Therefore, ensuring that the frost detection sensor functions correctly is crucial to prevent this issue.

8. Broken Blower Wheel

A broken blower wheel in a dehumidifier can significantly contribute to the phenomenon of freezing up. The blower wheel, which circulates air through the device, regulates the dehumidifier’s temperature and moisture content. When the blower wheel is damaged or malfunctioning, it can impede the airflow and disrupt the heat exchange process, causing the evaporator coil to become excessively cold.

As a result, the moisture in the air may freeze on the coil, obstructing further moisture removal and leading to a buildup of ice that can damage the unit.

Moreover, the reduced airflow caused by the broken blower wheel can also cause the compressor to overwork, resulting in increased energy consumption and reduced efficiency. Therefore, it is essential to promptly repair or replace a broken blower wheel to prevent freezing up and ensure optimal dehumidifier performance.

9. Malfunctioning Bi-metal Thermostat

A malfunctioning bi-metal thermostat is a common cause of dehumidifier freezing as it disrupts the proper temperature regulation within the device. The bi-metal thermostat comprises two metals bonded together, expanding or contracting at different rates as the temperature changes. This differential expansion causes the thermostat to bend, triggering the compressor to turn on or off as required. However, if the bi-metal thermostat becomes faulty or damaged, it may fail to accurately detect the temperature, resulting in an incorrect response from the compressor.

This can cause the evaporator coil to become too cold, leading to the condensation on the coil to freeze, obstructing the airflow and ultimately resulting in the freezing of the dehumidifier. To prevent this issue, it is essential to periodically inspect the bi-metal thermostat and replace it if necessary to ensure the proper functioning of the dehumidifier.

10. Low Refrigerant

Low refrigerant levels can significantly impact the performance of a dehumidifier and even lead to freezing up. Refrigerant, which undergoes phase changes to transfer heat, plays a vital role in dehumidification by cooling the evaporator coil.

When the refrigerant levels are insufficient, the evaporator coil may not reach the required temperature to extract moisture from the air, causing the collected moisture to freeze on the coil. This ice buildup restricts airflow and further impedes the dehumidifier’s ability to remove moisture, eventually leading to a complete halt in its operation.

In addition, low refrigerant levels may cause the compressor to work harder, leading to increased energy consumption, reduced lifespan of the appliance, and potential damage to other components. Therefore, monitoring the refrigerant levels and promptly addressing any leaks or malfunctions to prevent freezing and ensure optimal dehumidifier performance is crucial.

11. Mechanical / Electrical failures

Mechanical or electrical failures can significantly impact the performance of a dehumidifier, leading to issues such as freezing up. For instance, if the compressor or motor of the dehumidifier malfunctions, it may fail to circulate the refrigerant properly, causing the evaporator coil to become excessively cold.

As a result, the collected moisture can freeze on the coil, impeding the airflow and reducing the dehumidifier’s efficiency. Similarly, faulty sensors, switches, or circuit boards can disrupt the functioning of the humidistat, preventing it from effectively regulating the dehumidifier’s operation.

This can result in prolonged operation or inadequate humidity removal, leading to ice buildup on the coils. Furthermore, worn-out components or clogged filters can obstruct the airflow, causing the temperature inside the unit to drop and the moisture to freeze. To prevent mechanical or electrical failures from causing freezing up, regular maintenance and timely repairs are crucial.

12. Dirty Coils

Dirty coils can indeed be a contributing factor to the freezing up of a dehumidifier. The coils in a dehumidifier, both the evaporator and the condenser, facilitate the heat exchange necessary for dehumidification. If these coils become clogged with dirt, dust, or other debris, the airflow through the unit can become restricted, leading to a drop in temperature and potentially causing the moisture to freeze on the coils.

As ice accumulates on the coils, it can further impede the airflow and exacerbate the problem, eventually leading to a complete freeze-up of the unit.

To prevent this issue, it is essential to regularly clean and maintain the coils, either through manual cleaning or by using a coil-cleaning solution. The dehumidifier can operate efficiently and effectively without freezing up by keeping the coils free of obstructions.

How to Defrost The Dehumidifier?

Defrosting a dehumidifier is a simple process that can help address the issue of freezing up. Here are the steps to follow:

  • Turn off and unplug the dehumidifier: Before attempting to defrost the unit, ensure it is completely turned off and unplugged from the electrical outlet.
  • Let the ice melt: Allow the dehumidifier to sit and defrost naturally. Depending on the severity of the freeze-up, this may take several hours to a full day.
  • Remove excess water: Once the ice has melted, excess water may have collected in the reservoir or on the coils. Use a towel or cloth to absorb any standing water.
  • Clean the unit: Take this opportunity to clean the dehumidifier’s coils, fan, and other internal components. Use a soft brush or cloth to remove any debris or buildup contributing to the freeze-up.
  • Restart the unit: After the dehumidifier is completely dry and cleaned, plug it back in and turn it on. Check that the fan is running smoothly and the temperature is gradually increasing.

Following these steps, you can effectively defrost your dehumidifier and prevent future freezing issues. It’s also essential to identify and address the underlying causes of the freeze-up, such as low ambient temperatures or dirty coils, to ensure the proper functioning of the unit.


In conclusion, a dehumidifier is essential for managing indoor humidity levels but can experience issues such as freezing up if not properly maintained. Freezing up results from various factors, including low temperatures and dirty coils, and can impede the unit’s efficiency.

Regularly cleaning and maintaining the dehumidifier’s internal components, including the coils and fan, is essential to prevent freezing up and maintain optimal performance. In the event of a freeze-up, defrosting the unit and identifying the root cause of the issue can help prevent future occurrences. You can ensure a comfortable and healthy indoor environment by taking proactive measures to maintain the dehumidifier.

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