A standard dehumidifier representing how a dehumidifier functions.

Do Air Conditioners Dehumidify?

dehumidifierIn the summertime, the heat brings humidity to many homes around the US. Humidity is a result of moisture in your home, which can come from a variety of sources. During summer, however, the weather brings moisture with it and combines with moisture you create in your home passively. Moisture can lead to health problems, such as allergic reactions to mold and mildew. Mold and other fungi are fond of wet areas, making your basement the ideal place to grow. Your AC does some dehumidification, but that’s not its primary function.

Air conditioners work by pulling air out of your home via return ducts, cooling the air, and then recirculating it throughout your home. But sometimes all your home needs is dehumidification. Along much of the East Coast, including Pennsylvania, Maryland, DC, Delaware, and New Jersey, a lot of our heat is unbearable because of the humidity levels in the air. The sticky, thick 90º weather is awful, but when the humidity finds its way inside our homes, sometimes all you need is the movement of air. Ceiling fans are a common choice in homes with temperatures around the upper 70ºs. A ceiling fan can reduce the temperature you feel in the room by up to 10º in some cases. But do air conditioners dehumidify your home or just cool it?

Air Conditioner’s Functions

The short answer is yes, but that’s not the air conditioner’s primary function. An air conditioner’s core function is to cool the room. In order to do this, it pulls the air into the system and runs it over refrigerant-filled coils to cool the air. After going through the AC process, the cool air is sent back to the room(s) while the heat extracted from the air is expelled to the outdoors.

On the other hand, a dehumidifier’s core function is to remove the moisture from the air. In order to do this, the dehumidifier pulls the air into the system, cools it, heats it, and dispels the moisture into a bucket or a drainage system.

Both air conditioners and dehumidifiers make a room more comfortable. Both also pull moisture out of the air, but air conditioners do it passively, making them significantly less efficient than dehumidifiers.

Do I Need a Dehumidifier?

In Pennsylvania, we can have hot and humid summer days, but only for about 3 or 4 months in the year. The other 9 months are spent in ice, snow, heavy winds, and heavy rains. Depending on your climate, this may not be the case. For example, a home in Jacksonville, Florida sits in a climate with humidity levels of over 50% nearly every day, all year long. In fact, the average humidity levels in 2010 were 75.8%. In these climates, a dehumidifier is absolutely necessary.

For our neighbors in Pennsylvania and the majority of the country, it’s likely that all you need is a properly sized AC unit. If the unit is too large for your home it will kick on, cool your home quickly, and shut off. Not only is this not efficient or healthy for the system, but it’s also not doing any dehumidifying. It takes about a half hour for an AC unit to effectively remove moisture from your home. If the unit shuts off before this point, you’ll notice no difference in the humidity levels of your home. A unit that runs constantly will pull moisture from the air. If your unit runs fairly often, then you generally will not need a dehumidifier.

Homes with More Humidity than Normal

In some cases, homeowners experience more humid home environments than most of us. If you live in a humid home, then try one of the following:

  • Buy a portable dehumidifier – A portable dehumidifier can be very helpful when placed in rooms that produce the most moisture. Some central ACs have a setting to circulate the air throughout your home, but not necessarily cool it. The mode is called “fan mode” on most systems. If the system is in fan mode, the moisture produced in the shower, basement, or other moisture-producing places is recirculated to the rest of the home. Place the dehumidifier in these rooms to reduce or even remove the moisture from the air before it is recirculated.
  • Dehumidifying heat pipes – One fairly easy solution is to install a dehumidifying heat pipe onto your central AC. This heat pipe will act as a dehumidifier when the AC pulls air into the system. In fact, it can remove up to 91% of the moisture from the air flowing through the system, according to the Department of Energy.
  • Ventilation systems – One solution that’s often forgotten by homeowners is the simple one: ventilation. If the moisture is produced in the bathroom, make sure you have a good ventilation fan. Also make sure the fan is running when it needs to be. Ventilation systems can suck the moisture right out of the room before it even reaches the AC.

All 3 of these solutions can be used in conjunction with one another, but only in extreme cases is that necessary. Remember, you still want some moisture in the air because dry air can cause skin irritation and difficulties breathing. The most affordable of the 3 is the portable dehumidifier. Depending on the size of the room you place it in, you may need a more expensive unit, but they generally don’t run higher than $200-$250.


We recommend a dehumidifying heat pipe with a higher thermostat setting. As the heat pipe causes the air to come out slightly warmer (barely noticeable) than it would without the heat pipe, it causes the system to work slightly harder as well. This can cause higher energy bills, but the temperature setting with the heat pipe is now unnecessary. A home with higher humidity at a temperature of 70º can feel the same as a home with lower humidity at a temperature of 75º. Bumping your thermostat up a few degrees can reduce energy costs. Only use a dehumidifying heat pipe if your home is larger-than-average (3000 sq. ft. and up).

If your home is less than 3000 square feet, a portable dehumidifier is definitely the best choice for you. Place this dehumidifier at the source of the moisture and you should begin to notice a difference almost immediately. It’s important to note that using a dehumidifier with an AC can cause higher energy bills as both units are trying to pull the same air.

All homes should have ventilation systems installed in bathrooms to remove moisture.

Last but not least, we always recommend you clean the air conditioner’s filter and have your AC maintained by a professional at least once or twice per year (start of the hot season and the end of the hot season). This can improve the efficiency of your system and make your home more comfortable.

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