Why Your Dehumidifier is Blowing Warm Air and How to Fix It

By: Evan Scoboria, Last updated: June 28, 2023

A dehumidifier can be a lifesaver in damp environments, effectively reducing humidity and keeping your living space comfortable. However, it can be puzzling when your trusty dehumidifier starts blowing hot air instead of maintaining the desired temperature. This unexpected situation might leave you wondering what's happening and how to remedy the issue. In this article, we'll explore the possible reasons for your dehumidifier blowing hot air and give you some practical solutions to address the problem. By understanding the inner workings of your dehumidifier and learning how to troubleshoot common issues, you'll be better equipped to ensure your home stays comfortable and moisture-free. So, let's dive in and find out why your dehumidifier might be turning up the heat!

Dehumidifier is Blowing Warm Air

The Inner Workings of Dehumidifiers

To better understand why a dehumidifier may be blowing hot air, it's essential to know how these appliances function. There are two main types of dehumidifiers: refrigerant and desiccant, so let's take a closer look at how each of these works.

Refrigerant Dehumidifiers

Refrigerant dehumidifiers, also known as compressor-based or condensation dehumidifiers, operate by pulling in moist air and passing it over cold evaporator coils. As the air cools, the moisture in the air condenses into water droplets, which collect in a drip tray or bucket. The now-drier air is reheated by the dehumidifier's condenser coils and expelled back into the room. It is important to note that refrigerant dehumidifiers naturally produce some heat as a byproduct during this process. The heat generated by the condenser coils helps to raise the temperature of the dehumidified air slightly, ensuring that the expelled air is not too cold. As a result, it is normal for a refrigerant dehumidifier to blow air that is somewhat warmer than the ambient room temperature.

Desiccant Dehumidifiers

Desiccant dehumidifiers use a moisture-absorbing material called a desiccant, typically silica gel, to extract water from the air. The desiccant is housed within a rotating wheel or drum, absorbing moisture as the air passes. The moisture-laden desiccant is heated to release the captured water vapor, vented outside or collected in a container.

Why Is My Dehumidifier Blowing Hot Air?

If your dehumidifier blows hot air, it could be due to several factors. Here are some possible reasons and solutions:

Clean Your Dehumidifier's Air Filter

One of the key factors contributing to a dehumidifier blowing hot air is a dirty air filter. The air filter is an essential component of the dehumidifier, designed to capture dust, allergens, and other particles present in the air before it passes through the cooling coils. Over time, the air filter can become clogged with debris, restricting airflow and causing the dehumidifier to work harder to maintain optimal performance.

When airflow is restricted, the dehumidifier's compressor and motor may overheat, increasing the expelled air's temperature. Moreover, a dirty air filter can also compromise the dehumidifier's efficiency, causing it to consume more energy and struggle to maintain the desired humidity level.

To prevent these issues, cleaning the air filter regularly is essential. Follow these simple steps to maintain your dehumidifier's air filter:

  1. Unplug the dehumidifier and remove the air filter according to the manufacturer's instructions.
  2. Vacuum the filter gently to remove loose debris.
  3. If the filter is washable, rinse it under lukewarm water to remove stubborn particles. Avoid using harsh detergents or chemicals that could damage the filter.
  4. Allow the filter to air dry completely before reinstalling it in the dehumidifier.

Check your dehumidifier's user manual for specific recommendations on how often to clean the air filter. Regular maintenance will ensure that your dehumidifier operates efficiently and minimizes the chances of blowing hot air.

Clean Your Dehumidifier's Evaporator Coil

A dirty evaporator coil is another potential cause of a dehumidifier blowing hot air. The evaporator coil is critical in dehumidification, as it cools the air and condenses moisture into water droplets. Over time, dust, dirt, and other debris can accumulate on the evaporator coil, reducing efficiency and causing the dehumidifier to work harder.

When the evaporator coil is dirty, it becomes less effective at cooling the air, which can lead to inadequate dehumidification and a noticeable increase in the temperature of the expelled air. Furthermore, a dirty evaporator coil can strain the dehumidifier's compressor, leading to higher energy consumption and even potential damage to the unit.

To maintain the efficiency of your dehumidifier and prevent it from blowing hot air, clean the evaporator coil following these steps:

  1. Unplug the dehumidifier and remove any access panels to access the evaporator coil, following the manufacturer's instructions.
  2. Use a soft brush or vacuum cleaner with a brush attachment to gently remove dust and debris from the coil's surface.
  3. If the coil is filthy, you can use a specialized coil cleaner available at most hardware stores. Please follow the product's instructions carefully and ensure proper ventilation during cleaning.
  4. Once the coil is clean, reassemble the dehumidifier and plug it back in.

Remember to consult your dehumidifier's user manual for specific guidance on cleaning the evaporator coil and any recommended maintenance schedules. Regular cleaning will help ensure your dehumidifier operates efficiently and minimize the risk of blowing hot air.

Thaw Out Your Dehumidifier

If your dehumidifier blows hot air, the unit may have frozen entirely. When the evaporator coil is too cold, it can cause frost or ice to build up on the coil's surface, reducing the efficiency of the dehumidification process and leading to warmer expelled air. This issue is prevalent in refrigerant dehumidifiers operating in colder environments, where the temperature of the air being drawn in is already relatively low.

To thaw out your dehumidifier and resolve the issue of hot air, follow these steps:

  1. Turn off and unplug the dehumidifier. Allow it to sit for a few hours to melt the frost or ice. Be sure to place a towel or tray under the unit to catch any dripping water during this process.

  2. If the ice buildup is particularly severe, you can use a hairdryer on a low heat setting to gently and evenly melt the ice. However, please be careful when using a hairdryer near electrical components, and never use it on a plugged-in dehumidifier.

  3. Inspect the area around the evaporator coil for any debris or dust buildup that may have contributed to the freezing issue. If necessary, clean the coil as described in the previous section.

  4. Once the dehumidifier has fully thawed, plug it back in and turn it on. Monitor the unit closely for any signs of further ice buildup or hot air.

To prevent future freezing issues, consider adjusting the humidity settings on your dehumidifier, relocating the unit to a warmer area, or using a dehumidifier designed explicitly for low-temperature operation. Regular maintenance and cleaning will also help ensure optimal performance and reduce the risk of ice-related problems.

Troubleshooting Hot Air in Dehumidifiers

Randomly Turns Off

If your dehumidifier randomly turns off and blows hot air, it could be due to a faulty thermostat, overheating, or an issue with the auto-shutoff feature. Check the thermostat and make sure it's set correctly. If the problem persists, consult the user manual or contact the manufacturer for further troubleshooting.

Strange Sounds

Unusual noises from your dehumidifier, accompanied by hot air, may indicate a mechanical problem. The compressor, fan motor, or other internal components might be malfunctioning. In this case, it's best to consult a professional technician to diagnose and repair the issue.

Unresponsive Unit

If your dehumidifier blows hot air and becomes unresponsive, it could be due to an electrical issue, such as a blown fuse or a faulty power cord. Ensure the unit is securely plugged in, and inspect the power cord for any visible damage. Replace the fuse or have a professional examine the unit's electrical components if necessary.

Warm Coils

Warm coils in a dehumidifier can result in hot air being blown out. This issue may be due to low refrigerant levels, a leak, or a malfunctioning compressor. If you suspect any of these problems, it's best to contact a professional technician to assess the situation and provide the necessary repairs.


Dehumidifiers play a crucial role in maintaining a comfortable and healthy indoor environment. When they start blowing hot air, it can be confusing and concerning. Understanding the common causes of this issue, such as dirty filters, frozen coils, or mechanical problems, can help you identify the best solution. Regular maintenance and proper usage can also prevent many issues from arising in the first place, ensuring your dehumidifier operates efficiently and effectively.