High humidity inside the house is a huge problem. The air of your home feels wet, heavy, sticky, and steamy; it smells musty, and you have clammy skin. 

Humidity creates severe discomfort and also poses health risks. So it’s crucial to get rid of high humidity, and your air conditioner unit can help you with that. In this article, we will talk about the reasons why your house may feel humid with AC running.

Oversized AC unit, fast running thermostat fan, dirty evaporator coil, leaked duct or refrigerant, etc., can cause your AC not to reduce humidity properly. Besides that, AC is not sufficient enough to dehumidify your home in highly humid areas. Use a dehumidifier to decrease humidity most efficiently. 

house feels humid with ac running

What Happens When My House Is Too Humid Due To Air Conditioner?

Well, the first problem is discomfort. The air of our house will be heavy but warm. Mirrors and windows will be foggy. Your ceiling might have wet, corroded stains, and your paint may discolour and peel off. Other problems may occur too-

Bacterial and Fungal growth

Bacteria and fungus prefer a humid atmosphere for developing and reproducing appropriately. So in high humidity, you can see bacterial and fungal attacks on your walls, your furniture, especially wooden ones, and on your food. Your food will rot and spoil quickly in high humidity. 

Insects and Mites infestation

High humidity is like a heaven for insects. They thrive very quickly in this kind of atmosphere. So you can see ant and termite colonies in your closet, and you might have a bedbug infestation. 

Another insect that can thrive is house dust mites. They induce allergic reaction and causes sneezing, runny nose, itchy nose, and nasal congestion. Dust mites are a dominant means of causing asthma in America, and these mites can’t survive under 45% relative humidity. 

Electronics damage

Humidity can damage electronic machines. Water can condense near electric openings and give you lethal electronic shocks in extreme levels of moisture. It can also cause short circuits in electronic devices. 

Negative Health Effects

Excessive humidity will make your skin clammy, meaning you will sweat a lot, and it will not evaporate. As a result, you might catch a cold. You can also have severe headaches, chronic coughs, and watery eyes.

Bacterial and fungal spores can cause allergic reactions in your body. Dust mites can cause allergies and asthma. You can also suffer from food poisoning by eating bacteria cultured food.

Can An AC Make A Room Humid?

The short answer is no. Air conditioners make the air cooler, and cooler air allows less vapour dissolving. So actually, AC extracts humidity from the air by cooling it, making the air less humid. So AC reduces humidity. 

Why Is My Room Humid With AC On?

AC is supposed to reduce the humidity of a room. If your room is humid while the AC is running, it means your AC is cooling the air but not removing the moisture effectively. In other words, your AC is not dehumidifying.

Why Is My AC Not Dehumidifying?

It can happen due to various reasons. We will elaborate on the reasons mentioned before.

Oversized AC unit

This is a common problem in America. The evaporator coil of your AC cools the air and extracts humidity from it. But for efficiently removing the moisture, the AC needs to run for a long time. 

If your air conditioning unit is too large compared to your house, it can cool the air of your home in a short time. So the AC will turn on and off multiple times instead of running continuously. These short cycles hamper humidity extraction.

Too small AC can create problems in the same way. So it would help if you had the perfect sized AC for your house. A professional can help you with this matter.

Dirty Evaporator Coil

The evaporator coil inside AC contains condensed gas that cools the air and liquefies humidity. So if the evaporator coil is dirty, It becomes inefficient. 

The solution is to keep your evaporator coil clean. You can clean the coil yourself, but we highly recommend hiring a professional. 

Hiring a professional regularly to keep the AC clean might sound like a hassle. To avoid this problem, you can install an air filter inside AC. The filter will soak the dirt and small particles, so they won’t reach the evaporation coil and make it dirty. Plus the air of your house will be cleaner, so it’s a win-win!

Fast Thermostat Fan

The thermostat fan moves the cool air into your house. If it moves slower, the air will be in contact with the evaporator coil for a longer time. So the coil will be able to extract humidity from the air more efficiently. But if the fan moves faster, it will fan the humid air out shortly. So for moisture removal, a faster rate is not preferable. 

But some air conditioning systems are designed to run at faster rates by default. You can manually set a lower speed to solve the problem. Or an AC with a variable speed feature will automatically resolve this issue.

Leaked Duct or Refrigerant

Duct leakage is another common problem. According to energy.gov, up to 30% of conditioned air is lost to leaky ducts.

Most people keep the AC in the attic or basement. So the humidity can crawl in from these places to the duct through these leaks.

You can figure this one out by inspecting your ductworks and sealing out the leaking ducts.

Similarly, you can have leaked refrigerant. This is a much severe problem, and your whole AC will start to malfunction and make noises. Only a professional can fix this issue.

How Do I Fix The High Humidity In My House?

In many cases, your AC might not be enough to solve the humidity problem. There are many alternative ways to solve the humidity problem.


The best and most efficient way to solve the moisture problem is to buy a dehumidifier. This device soaks water vapour from the air, liquefies it, and dumps it through a channel. It can help you evenly balance out the humidity of your whole house to a healthy level. 

You must contact a professional before buying a dehumidifier. It’s vital to find the perfect sized and perfect powered dehumidifier suitable for your home. An overpowered dehumidifier can soak too much humidity that can cause many other problems.

A smart dehumidifier will also allow you to set the humidity level of your preference. 

Thermal Expansion Valve (TXV)

For better moisture management, you can install a Thermal Expansion valve inside your air conditioner unit. A TXV increases the surface area of the evaporator coil. So the evaporator coil can withdraw moisture more quickly and efficiently.

Appropriate Ventilation

Humidity production is totally normal. Many of our daily lives work like cooking, bathing, washing, and even breathing produces humidity. But some rooms like laundry, kitchen, bathroom, etc., naturally generate more moisture. Appropriate ventilation allows the extra moisture to go outside, keeping the indoors healthy. 

You must have a sufficient amount of doors and windows. Install exhaust fans in the rooms that produce more moisture. The exhaust fans will pull out warm moist air from the rooms. Also, check your dryer vent regularly to make sure it’s working correctly.


Make sure the pipes of your house are appropriately insulated. Coldwater pipes can condense water in summer, and insulation prevents that. 

Dripping water can evaporate and cause high humidity. Proper insulation can also prevent water dripping. 

Also, insulating the walls properly will close the small gaps where moisture can build up. So proper insulation of walls can also help.


Weatherstripping means treating edges of doors and windows with adhesive to create an air-tight seal. This stops cool air from escaping out and humidity from getting inside. 

Lifestyle Change

Keep the doors and windows open for a while and let the humidity pass out, allowing fresh dry air to blow in. Turn on the exhaust fans when using the bathroom, cooking, or washing clothes. 

These minor lifestyle changes will help you maintain a healthy atmosphere. 

How Do I Lower The Humidity In My House With AC?

As mentioned before, firstly you will have to buy the perfect sized AC unit for your house. Take the help of professionals in this matter. Then you need to ensure leak-proof ductworks and vents. Practice preventive maintenance to keep the evaporator coil, thermostat fan, and compressor clean and adequately functional. 

Manually set the thermostat fan to run at a slower speed. And lastly, you can install a Thermal Expansion Valve in your AC for better humidity control.


House feels humid with AC running? Well, hopefully, now you know the reason behind this and ways of efficiently preventing it. We hope this article will guide you towards a more healthy lifestyle and make your home atmosphere sound.

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