Why Does My Window or Portable Air Conditioner Increases Humidity?

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Air conditioners(both window or portable) can sometimes, increase the humidity and make the air feel uncomfortable for the dwellers. 

If you face this type of situation there is no need to be alarmed. Because this is a very common and fixable situation.

So, does a window or portable air conditioner increases humidity? 

Yes, a window/portable air conditioner can increase humidity. This could happen because of the ‘fan’ option on and the AC being too big or too old. A dirty evaporator coil can also cause this to happen. Changing the ‘fan’ option to ‘auto’, and cleaning the evaporator coil can fix the problem.  

These problems are still very new to you, and we’ve tried to make them as understandable as possible in the following sections.

Why is the Window Air Conditioner Increasing Humidity?

Air conditioners are meant to remove humidity. So, we understand how frustrating it can get when it does the exact opposite.

Window Air Conditioner Increasing Humidity
Source: thespruce.com

Here are the answers to why ac is cooling but not removing humidity

Reason 1: ‘Fan’ On in Thermostat Settings

There is this misconception about having the fan on in the thermostat settings. It is often thought that keeping this option on will make the air cooler. 

Although it does for a while, but it continues to increase humidity in the process. Especially, when the fan runs for 24/7, It brings humid air into the house, even when the AC is turned off.


So how to decrease humidity in an air conditioner when it’s because of the fan? 

To decrease humidity in an air conditioner just switch the mode from ‘fan’ to ‘auto’. This option commands the fan to operate only when the AC is turned on.

The indoor coils accumulate water on top of it. And this being released into the air makes it humid. So, this change in thermostat settings also stops that from happening. 

Reason 1: Wrong Size of AC

Another misconception is that owning bigger-sized ACs means it will make the space colder. And not just colder but also the cooling will be faster. But unfortunately, that isn’t the case. 

Rooms not having the proper sized AC tends to overwork it. Because of this, the compressor turns on and off constantly. As a result, the dehumidifying feature in the AC can’t cope up and ends up increasing the humidity of the room.

Constant turning off and on is called short cycling. During the short cycle, the AC doesn’t even complete a full cycle. Because of this, it doesn’t extract moisture and cooling doesn’t stay uniform. 


One solution to this is replacing it with a smaller AC. Though it’s expensive but effective in the long run.

proper sized AC
Source: nytimes.com

Checking how much BTU your air conditioner comes with, has to be equal to the BTU your room requires to cool. If it’s a perfect match, the humidity will be balanced as well.

Reason 3: Dirty Evaporator Coil

The main function of the evaporator is to cool and dehumidify. If the evaporator works properly it will absorb the moisture and exchange heat. If the evaporators becomes dirty, the clog obstructs them from doing their job properly. As a result, it will cool but not dehumidify. 


What you have to do to fix the dirty evaporator problem is clean the coil.

Start by removing the unit to find the evaporator coil. Once you find that use a cleaning agent to get the dirt and debris off the coil. 

Both the Lysol All-Purpose Cleaner and the Mrs. Meyer’s All-Purpose Cleaner Spray work amazingly well to get all the dirt off. 

Make sure to scrub a lot so that there is no dirt left. 

Reason 4: Old Air Conditioner Model

Yes, your AC being on your wall for too long is a problem. Most AC units have a lifespan of 10 to 15 years. After the timespan, the quality starts to decline. And for this, the AC starts to outdo its functionalities.

Not humidifying properly is one of those functions. The coil gets burnt out and doesn’t cool the air passing through it properly. This increases humidity and the AC unit at this point works harder to decrease it. 


The only solution for this is getting a new AC. Contact a professional if you notice you have an old AC and humidity is increasing. They can reassure you whether the AC needs replacing or not. 

Why Is Portable Air Conditioner Increasing Humidity?

Do portable air conditioners remove humidity? No, mostly they don’t. In fact, they increase it. Let’s take a look at the reasons-

Faulty System

Some portable air coolers use an evaporation system. This system is used to cool the air. The air is cooled by a fan blowing through an absorbent material that is soaked in water. 

The air becomes cold because of the water vapor. Side by side the humidity also goes up. 


When buying portable air conditioners try to not buy cheap ones. The cheap ones usually work in this way. The mechanism of the newer ones is not supposed to increase humidity. 

If you find that your portable ac has a faulty system then either you have to replace the main system or replace the whole ac altogether. If you’re looking for good quality portable ac then I have a few favorites-


The weather is a huge factor when it comes to increasing humidity. In tropical areas, portable coolers tend to raise humidity. On top of that, because of the moist air, they don’t function well. 

Now you might be thinking, do portable air conditioners work in dry climates? The answer is yes, they do. 


Check the atmosphere you’re in. if you do live in a tropical environment avoid portable air conditioners. Try getting a good quality split ac. 

Another thing you can do is get a 2 pipe unit. 1 pipe will bring in the required air. Another one will drain the produced warm air. This will give you the proper operations! 

Some Other Solutions to Humidity Problem 

Let’s take a look at some other ways that you can prevent or solve this problem. 

Get a Dehumidifier

Installation of a dehumidifier can help big time in this type of situation.

But as you’re experiencing right now they sometimes fail to. This solution can be best for when the only solution you have is getting a new AC. And that can be expensive at times.

do window ac units dehumidify
Source: phys.org

There are a lot of dehumidifiers on the market as of now. But we’d suggest investing in a good quality dehumidifier. 

Routine Maintenance

Your future self will thank you for the constant check-up of the AC. This will save you a lot of money and time later on. Because of this routine maintenance, you can check if anything is broken. 


Why is the humidity so high in one of the rooms of my house?

The reasons could be blocked air vents, not good ventilation, no windows, etc, Ventilation is very important for any room hence the room should be designed in that manner. The weather could be a huge factor too. 

Is 70 a very high number in the case of humidity?

Building Science Corporation research indicated that 70% humidity or greater can cause property damage. Health and Safety say 40-70 per cent relative humidity indoors, whereas some experts propose 30-60 per cent.

Is it possible to reduce humidity without a humidifier?

Yes, it is possible to reduce the humidity without a humidifier. You can open your windows, put the plants outside, dry your laundry outside, take cold showers, you can put a basket of charcoal, etc. 


From all of this discussion, we have understood that Window or portable Air Conditioner Increases Humidity. And there are many ways to decrease it as well. So, don’t stress over it too much. 

Even if getting a new AC is not convenient at this point, we’ve hopefully given alternatives that will suit you. Good luck!

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