Dehumidifier Blowing Hot Air? Causes & Solutions

While so many household appliances have made our lives easier, it would be difficult for us to learn each one’s function and characteristics. Many people, for example, are baffled when they notice their humidifiers are blowing hot air.

Calm down! In normal operation, most humidifiers produce warm air but not excessively hot air. If your machine is blowing too hot air, you may need to clean the filter or coil, allow it to cool down, or consider purchasing a new one.

This is a brief response. This post will explain why a dehumidifier can blow warm air, the causes of hot air in a dehumidifier, and how to properly fix the problem.

 Let’s get started!

Why does my dehumidifier blow warm air?

As I mentioned earlier, it is normal for a dehumidifier to blow warm air. In this section, I will explain why this is so.

To understand why your dehumidifier produces warm air, you must first understand how a dehumidifier works.

Because compressor models (also known as refrigerant dehumidifiers) are used by the majority of American families, we will first address it.

A compressor dehumidifier can lower the indoor humidity level because it can remove the excess moisture through a condensation process.

It draws air into the machine with the help of a built-in fan. The cold coil can cool the air below the dew point when warm air passes through the evaporator coil. The water vapor will then condensate and accumulate in the water tank.

The air is dry and cool right now, but it will be reheated after passing through the hot condenser coil. 

As a result, the exhaust air will be slightly higher than the air in the room when it returns to the room. Unlike a dehumidifier, an air conditioner will blow cold air into the room.

If you have a modern desiccant humidifier, it can also blow out warm air. This is because the air gets dry and warmer after it passes through the rotor and it will be expelled into the room directly.

A dehumidifier can’t cool a room but could make you feel colder because of the decrease in humidity level.

How hot should the air coming out from the dehumidifier be?

You may wonder how hot the exhaust air is under normal conditions. After all, there should be something wrong when the air gets too hot. 

Normally, the dehumidifier can raise the air temperature by 5°F to 15°F. Use a hygrometer to inspect the ambient temperature and output air. If the difference exceeds 15°F, it is too hot, and you should take measures to find the cause and fix it. 

Another way to judge is that the output air should be around 70°F to 90°F.

Why is your dehumidifier blowing excessively hot air?

Now, it is time to explore the causes of excessively hot air. Some culprits you may have never thought about them before. 

1. Dusty air filter

The air filter in the dehumidifier sits in front of the evaporator coil and is responsible for filtering out dust and dirt. It must be replaced or cleaned on a regular basis, depending on how frequently you use it and the air quality in your home.

When it is clogged, less air flow will go through the evaporator and condenser coil. It means that the heat produced by the condenser coil is too much for such a low level of airflow, which will result in the exhaust air getting too hot. 

2. Dirty evaporator coils

Evaporator coils can accumulate a lot of impurities over time. When it is dirty, it will impede the efficiency of this dehumidifier in cooling the air down. The coil will even freeze up.

When air comes into contact with the coil, the coil will not be able to cool down below the dew point. It will lead to less removed moisture and make the air leaving from the evaporator coil to have a higher temperature than usual. 

Thus, after passing through the condenser coil, the air will be reheated to a higher temperature.

3. Leaking refrigerant

Compressor humidifiers utilize refrigerants to facilitate the heat transfer process. When the refrigerant leaks, it will cause the evaporator coil to become less capable of cooling such an amount of air.

So the air may still be warm before passing through the condenser coil. When it goes through the condenser coil, it will be reheated and get even hotter.

4. Your dehumidifier is overloaded

When your dehumidifier is too small, or the environment gets too humid suddenly, your dehumidifier will continue to work with the maximum power. 

If it keeps running, the machine will get overloaded, making it unable to remove moisture and the air temperature rise.

5. The water bucket is full

dehumidifier full of water

While there are many ways to drain a dehumidifier, a proportion of people still choose to dump the water manually. 

These days, many models can shut off automatically when it detects the water reservoir is full. Some models, however, will stop collecting water but continue to run the fan, or it can’t detect the state of the water tank. 

Under these circumstances, the air temperature does not drop when it passes through the evaporator coil, causing you to feel hot. When the temperature in the room is high, you will notice that the air blowing out is warmer.

6. Damaged components

A dehumidifier is not something that is immune to tear and wear. With time, it can get overheated and faulty. When some components fail, it can disrupt the machine’s normal operation, causing it to produce air that is too hot or too cold.

How to fix a dehumidifier that blows excessively hot air?

To fix this issue, you may be able to get it done on your own or need to call in an HVAC professional. I will illustrate the solutions to each cause below.

Clean or replace the filter regularly

Cleaning or replacing the air filter regularly is a simple but effective way to ensure that your machine gets sufficient airflow.

Every month, you can take out the filter and rinse it under the water to get rid of the contaminants. You need to replace it every few months, depending on how dirty it gets.

Clean the coils 

If the problem is caused by a dirty coil, you will need to disassemble the unit, access the coil, and then clean it.

A damp cloth will not always suffice to clean it. Instead, you must use a coil cleaner.

After that, let the coil air dry and put the machine back. 

Drain the water in time or change to another drain method

If the fan of your model will continue to work when the water tank is full, you should drain the water in time. 

Those who are tired of dumping the water can open the drain port on the back and connect it to a drainage hose, allowing the water to continuously flow out to the floor drain.

Defrost the machine

When the air filter or evaporator coil is clogged, the machine will blow hot air. In the meantime, it will cause the device to ice up.

Allow the machine to thaw and test it again once you notice it.

Turn off your machine when it runs too long

When your machine is overworked, your best bet is to turn it off and let each component has adequate time to cool down. 

Hire a pro

If none of the above solutions work, you should contact the manufacturer or hire a professional to repair it. Do not attempt to replace the components on your own as this may void the warranty or cause other problems.

Buy a brand new model

The cost of repairing a humidifier that blows hot air may be greater than the cost of purchasing a new one. If this is the case, or if the machine has served you for a few years, replacing it is a much better option.


This post discussed why your dehumidifier blows hot water and how to fix it.

It is normal for a humidifier to blow warm air because the condenser coil reheats the air before it returns to the room. When it gets too hot, however, you should exercise caution.

The most common causes are a dirty filter and clogged coils. A machine that runs too long or has a full tank of water can occasionally blow hot air.

If the issue is with the internal components, you should hire an HVAC professional rather than attempting to fix it yourself.

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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 a lot 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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