Does Air Conditioning Reduce Humidity? Yes! Here’s How (And How Much)

It’s impossible to engineer an air conditioner without simultaneously engineering a dehumidifier.

Air conditioners and moist removal. Do air conditioners dehumidify? It is quite surprising how many homeowners want to know if their AC removes humidity. What is even more surprising – and not at all apparent – is that all air conditioners reduce humidity. Basically, they work like dehumidifiers in addition to providing cooling output.

Example: Let’s say you have a home with 80°F indoor temperature and 75% relative humidity levels. You turn on an air conditioner (be it a mini split, central, window, or portable unit). In a matter of minutes, the temperature levels fall closer to 72°F. In a matter of minutes or hours (depending on several factors), the relative humidity levels fall below 40%.

relative humidity levels with air conditioner and without air conditioner

AC units are primarily designed to do one thing:

Reduce indoor temperatures.

In reality, air conditioners do a lot more than provide cool air. They also ventilate the air, filter it, and remove humidity.

air conditioner removing humidity by condensation
AC units reduce humidity levels by condensation (on indoor cold coils). This is the same effect we see when moisture is condensed on windows.

Air condition’s ability to reduce both relative humidity levels as well as the temperature make it a perfect device for places that are both:

  • Hot. Areas with above 100°F summer temperatures.
  • Humid. Areas with high outdoor humidity levels like Florida and East Coast in general.

In hot humid areas, ACs shine the brightest. They can tackle both problems – high temperature and high indoor moisture levels – simultaneously.

Let’s quickly look at how does AC removes humidity. On top of that, we will look at how much humidity does an air conditioner remove as well (to see how it compares to an actual dehumidifier):

How Does An Air Conditioner Reduce Humidity Levels?

The mechanism of action of all AC units is based on a refrigerant cycle. This involves the use of refrigerant (a gas/liquid with specific heat-transferring capabilities; R22 and R410A are two examples) that cycles between indoors and outdoors.

water condensation in refrigerant cycle for air conditioners
Depiction of a refrigerant cycle. The side-product of this cycle is indoor humidity reduction.

Of course, the main thing here is the transfer of cool air indoors. However, as a side effect of the mechanism of action of AC units, the humidity is removed (via condensation) and expelled outwards.

Here is how AC reduces humidity levels:

  1. Moisture condenses on indoor coils. Indoor AC coils are very cold. Moisture in the indoor air condensates on the cold coils.
    does ac reduce humidity
    Mini split AC. The moisture is condensed on the indoor cold coils.
  2. Condensed water is expelled outward via a drainage hose, evaporation through the air exhaust hose, or condensation tank (that has to be emptied manually).
  3. Effectively, the air conditioner removes moisture from indoor air and the humidity levels fall.
humidity removal by dehumidifier vs air conditioner
Depiction of a dehumidifier. The principle of humidity removal is the same as with AC units; moisture is condensed on the cold coils, water is gathered in a tank, and you get dry air.

Now, it is quite useful to understand how much humidity does an air conditioner remove:

How Much Humidity Does An Air Conditioner Remove?

Is the amount of water the AC unit is able to extract from indoor air significantly and reduces indoor humidity levels adequately? Or is the dehumidification function of AC units more or less symbolic, not significant?

AC units are quite good at reducing humidity levels. If you check the specs sheet of any AC unit, you will see a ‘Dehumidification Rate’ specification. The amount of water the AC unit can extract from indoor air is usually expressed in Pints per hour (Pt/h on the specs sheet).

Example: In this post about the best portable AC units, we have compared the dehumidification rates of portable air conditioners. The #1 Whynter ARC-14S Dual-Hose, for example, is a 14,000 BTU unit that has a max. dehumidification rate of 4.21 Pt/h. That means that, in ideal conditions, this AC unit can extract more than 100 pints of water (101 pints, to be exact; that’s 15 gallons of water) per day.

In short, air conditioners work as excellent dehumidification. In fact, if you have an AC on, you will likely not even need an additional dehumidifier to take care of the high humidity levels in the summer.

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