Should You Run A Dehumidifier And Air Conditioner At The Same Time?

Air conditioners and dehumidifiers are both useful appliances for increasing home comfort. Many people know how to use each separately but are unsure if they can work together.

Yes, you can use a dehumidifier and an air conditioner simultaneously. It can increase the efficiency of your air conditioner and help you save money on your utility bill.

But why and when should you use these two devices together? Can you use them alternately throughout the day?

Keep reading, and you will find a lot of helpful information about humidity, dehumidifiers, and air conditioning.

How does an air conditioner affect humidity?

As you know, the function of a dehumidifier is simple—lower the humidity level. In order to figure out how a dehumidifier will affect an air conditioner, you should first understand the relationship between humidity and an air conditioner.

The primary function of an air conditioner is cooling the room. The air will cool down when it passes through an evaporator coil which is similar to the one in a dehumidifier.

During this process, a portion of the water vapor is removed, resulting in lower humidity in the conditioned air. That is, an air conditioner naturally has a dehumidifying function.

However, dehumidifying is just a side function of an air conditioner, meaning that it would not be as effective as a dehumidifier in terms of controlling humidity. When running an AC in an extremely humid environment, the air may still be clammy even though the air temperature is relatively low. 

To make us feel comfortable, we should not only control the temperature but the humidity. Using a dehumidifier can make the room feel cooler because it can speed up the evaporation of our sweat, so we feel more comfortable even if the room temperature doesn’t change.

That is to say, we can set the target temperature higher when running an AC when the humidity is lower or just run a dehumidifier only when the air temperature is not so hot.

Based on what we discussed in this section, you can conclude that using them at the same time will supplement each other rather than cancel each other out.

Benefits of using a dehumidifier and an air conditioner together

Now that we have had a basic understanding of the working principles of these two devices. Let’s explore the benefits you can reap by using them together.

You will feel more comfortable

People use air conditioning in summer in most cases. Summer is hot and moist unless you live in a really arid place. While an AC can remove some excess moisture in the air, this is not its primary purpose. 

The indoor humidity level can drop faster if you run a dehumidifier with your AC. When the air gets drier, you will feel more comfortable because the heat in your body can disperse quicker. 

Furthermore, combining them can reduce the likelihood of dust mites and mold growth even further. These two substances can cause allergic reactions and other respiratory issues, but an air conditioner alone may not be able to keep humidity levels below 50% in some cases.

Improve efficiency

The efficiency of AC drops along with the increment of humidity level.

Many people have the experience that the AC in the hotel near the beach seems to be not as powerful as the unit at home. In this case, you may need to blame the humidity instead of the machine. It also means that the unit will work harder to maintain the room temperature, increasing the electricity bill numbers.

When running a dehumidifier together, the dehumidifier can be responsible for lowering the humidity, which can improve the efficiency of your AC.

In addition, it can reduce the tear and wear, prolonging the lifespan of your machine.

When to use a dehumidifier with an air conditioner?

when to use dehumidifier with air conditioner

While it is conducive to using them together, it doesn’t mean you should use this combo under every condition. Three scenarios are suitable for using them together. 

The air conditioning unit is too small

When the air conditioner is too small for the room, it cannot effectively cool and dehumidify it.

Running a dehumidifier can reduce the load on your air conditioner. Meanwhile, because a dehumidifier can make you feel cooler, your air conditioner doesn’t need to be set as low as it was previously.

Your AC is oversized

Some people find that their room is humid with the AC on. A small-sized unit can cause it, a oversized unit can lead to it as well. 

When the AC is too large, it can cool the air in a short time, meaning that it doesn’t have time to remove the excess humidity because it will shut off automatically when the target temperature is reached. 

As a result, an added dehumidifier can continue to dry the air, increasing your overall comfort.

Too humid

Outdoor humidity is constantly changing, and it has an impact on indoor humidity. When the weather becomes too humid and your air conditioner is unable to handle the moisture, you can turn on your dehumidifier.

Running these two devices together can make you more comfortable.

How to use a dehumidifier and air conditioner together?

Once you come across any scenario I mentioned above, you can use them together. But you can use them alternately or at the same time, depending on your preference and other factors.

At the same time 

If your air conditioner is unable to keep the humidity level below 50% while running, it is time to install a dehumidifier. You can continue to monitor the humidity level and decide whether to use the AC to easily handle the moisture.


Even if your AC can control the humidity level while running, you can choose to run a dehumidifier when it is off.

It will prevent the mold and dust mites from thriving. Meanwhile, you can save more money because you can set your AC at a higher temperature when the humidity is low.

That’s why adding a dehumidifier to the HVAC system is recommended because you can benefit a lot regardless of whether or not you run it with an AC.


Can you run a dehumidifier with an AC? Yes, you can! As a dehumidifier can remove excess moisture, your AC can work more efficiently, which can save your electricity charge. You will feel more comfortable as well. 

You can try to use them at the same time or alternately. Both are great ways to make the most out of these two devices.

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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