Do Air Conditioners Remove Humidity & How To Use It?

We all know how uncomfortable that sticky feeling can be. Summer days mean not only high temperatures but also high humidity. 

Because we use air conditioners to cool the air in the summer, many of us wonder if they can also reduce humidity. The answer is YES. Air conditioners, regardless of type, can reduce humidity to some extent.

But why can they reduce humidity, and how can you maximize their humidity-reducing effect? You need to know more details in this article.

Why does running an air conditioner reduce humidity?

To truly understand why an air conditioner can reduce humidity, you must first understand how it works.

An air conditioner lowers the room temperature by cooling the air that is already in the room rather than adding fresh cool air.

Because refrigerant can absorb and release heat when changing from liquid to gas and gas to liquid, it is used by the air conditioner to absorb heat in the air.

how does an ac reduce humidity

When warm air enters the interior of the air conditioning system, it passes through the evaporator coil. At this point, the refrigerant in the evaporator coil will absorb the heat in the air, causing it to cool.

Meanwhile, condensation occurs when the air temperature falls below the dew point, and water vapor in the air is converted to water, which drips into the water tray.

Because the excess moisture has been removed, the air returning to the room will be drier and cooler, gradually lowering indoor humidity.

How much humidity can an air conditioner remove?

Now that it has been established that air conditioning removes moisture, how much moisture does it remove?

Keep in mind that dehumidifying is a side function of any air conditioner, so don’t expect it to be as effective as a dedicated dehumidifier.

An air conditioner can typically collect between 5 and 20 gallons of water per day. Larger units, or those used in extremely wet areas, tend to remove more water.

A window air conditioner, for example, collects less water than a central air conditioning system.

How to use your AC to lower humidity effectively?

Again, the main function of an air conditioner is to cool the air. If you want to get the most out of it in terms of dehumidifying, you need to make some adjustments. 

Set the fan to “AUTO”

For those who use a central AC, you should check the fan settings on the thermostat. If you want to keep the indoor humidity level low, you should set it to “AUTO” because the fan will stop working when the AC turns off. 

Otherwise, the moisture left on the evaporator coil will continue to blow into the room because the fan will continue to spin even when the air conditioner is turned off.

Use Dry mode

Assuming you are using a split AC, then you can set it to “Dry Mode” when you want to reduce humidity.

When this mode is on, your AC will focus on dehumidifying the air, rather than lowering the temperature, by modifying the speed of the fan and compressor.

Lower fan speed

When the fan speed decreases, the evaporator coil will become colder because less warm air will be drawn into the machine. 

But it can promote the condensation process, which will remove more moisture. 

Clean the filter on a regular basis

A filthy air filter could be the culprit of an abundance of AC problems. It can trap moisture, impede airflow, make the coil freeze, and so on. Many of these problems will impair indoor air quality. 

Fortunately, most air filters only need removing, washing, and then replacing. 

Fix refrigerant leaks

As I stated previously, refrigerant is the core material that makes the cooling effect happen. Therefore, it is important to make sure there is enough refrigerant in the system. 

Under normal conditions, it stays untouched in the coils and compressor. However, it can leak out due to corrosion, extreme weather, or other factors.

There are some ways to check your AC’s refrigerant level. If you doubt it is running low, you need to call an HVAC specialist to look at it. Your machine may need a recharge.

Purchase a new unit

You may have gone through a situation where your house is humid when the AC is on. The reason behind this may be that your AC is too big or too small for your house or room.

When an air conditioner is undersized, it lacks the ability to lower the temperature sufficiently. Because it will always run at full capacity, its dehumidifying effect will be compromised.

When the air conditioner is oversized, it will cool the room quickly and then turn off, resulting in short cycling. That is, your air conditioner is not getting enough time to remove moisture.

Regardless of which situation you have, your best bet is to purchase a new unit with the proper size.

Turn on a dehumidifier 

If you are not in a position to purchase a new unit immediately, you can try running your AC with a dehumidifier together.

It will lessen the strain on your AC and remove excess humidity effectively. In case you don’t know, you can install a whole-house dehumidifier instead of running a room dehumidifier in each room.


After reading this post, I’m sure you’ve figured out whether or not your air conditioner can help with humidity. Even though dehumidifying is just a side function of AC, it can keep your house or room comfortable in most cases. 

To use your AC to control the humidity level better,  you can adjust the fan speed, turn on the “Auto” or “Dry” mode, and clean off the air filter. 

If your AC still can’t reduce humidity to a certain level, you should consider turning on the dehumidifier.

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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.