Can Mosquitoes Come Through Air Conditioner Vents?

It is annoying when a mosquito buzzing around my ear when I sleep. It makes me wonder, can mosquitoes come through vents? So, I did some research.

Mosquitoes can come through vents. Mosquitoes can enter through the fresh air vent of air conditioners and the exhaust vent of ventilation fans. However, an insect screen can be installed behind a vent to block mosquitoes and prevent them from entering through the vent into a house or building. All vents on the exterior wall should always have an insect screen to protect against insects’ intrusion.

Some people have a hard time figuring out how do mosquitoes get into their house and they don’t realize that it is the fresh air vent and the exhaust vent.

How Do Mosquitoes Come Through Vents?

Mosquitoes enter a fresh air vent of air conditioners or an exhaust vent of ventilation fans that is located on the exterior wall of a house or building. Then, they fly inside the duct that connects to the air conditioner or ventilation fan. Eventually, they’ll reach the end and come out from the air conditioner or ventilation fan where they’ll find themselves already inside a house or building.

Mosquitoes path from outdoor to indoor

The above sketch illustrated how mosquitoes enter through vents, travel inside the duct and finally, reach inside the house. Obviously, mosquitoes can’t enter the exhaust vent when you are running the ventilation fan in the bathroom or basement. However, when the fan is not running at night, mosquitoes can sneak in through the exhaust ductwork.

Similarly, mosquitoes can enter through the fresh air ductwork when the central air conditioner is not running. If the central air conditioner is running, mosquitoes that happen to be sucked into the vent will eventually block by the filter of the air conditioner. That’s why some people see their air conditioner filter has many insects and bugs stuck on it when they do the cleaning.

How to Prevent Mosquitoes from Coming Through Vents?

One simple solution to mosquitoes coming through vents is to install an insect screen behind the vent. An insect screen is a fine mesh that can be made of metal or plastic. Metal mesh is recommended because it is usually finer which can prevent smaller insects such as mosquitoes from entering the vent. It is hard to manufacture a fine mesh using plastic.

I recommend PartsExtra Louvered Grille Cover Vent with Fly Screen Mesh (click to buy from Amazon). It has a fly screen mesh that is fine enough to prevent mosquitoes. It is a durable vent designed for outdoor application with its body material made of stainless steel. Besides, its louvered grille is weatherproof which is very important to prevent rainwater from entering the vent which can rust the duct.

On the other hand, you can buy a metal mesh, cut it into shape and put it behind your external vents. Most of the time, it’ll work just fine. However, you may find it hard to install back because it was not designed to have an insect screen. But, if you press harder, it’ll fit too. Just be careful not to cut yourself or damage the steel mesh.

I found a video on YouTube where it demonstrates how to install the steel mesh onto a vent. I thought you may find it useful, so I embedded it.

Can Mosquitoes Come Through Window Air Conditioners?

Mosquitoes can come through window air conditioners. Mosquitoes can enter through the fresh air duct of window air conditioners. Some window air conditioners do not pass the fresh air through a filter to capture insects. Hence, it opens a passage for mosquitoes to enter the house.

Not all window air conditioners have a fresh air vent. Usually, window air conditioners that are above 10,000 BTU capacity have a fresh air vent where you can toggle it on to bring in outside air. However, some window air conditioners take in outside air and supply it directly into a room or house without passing through a filter. Hence, mosquitoes can easily come through the fresh air duct of window air conditioners.

To overcome, try to put a small piece of washable filter on the fresh air vent. Alternatively, you may choose not to open the fresh air vent at night where mosquitoes are more active.

Can Mosquitoes Come Through Split Air Conditioners?

Mosquitoes cannot come through split air conditioners. The indoor unit and outdoor unit of the split air conditioner are connected by a set of refrigerant pipes. A refrigerant is flowing inside the refrigerant pipe in a closed loop. Hence, there is no opening for mosquitoes to come through split air conditioners.

However, if a split air conditioner has a fresh air vent, mosquitoes can come through the fresh air vent just like the central air conditioner. Wall mount type split air conditioners are often not compatible with a fresh air duct. But, ceiling cassette and ceiling concealed mini split air conditioners are known to have a fresh air duct.

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Are Mosquitoes Attracted to Air Conditioning?

Mosquitoes are not attracted to air conditioning. Mosquitoes don’t like staying in air-conditioned rooms due to the cold and dry climate. Mosquitoes prefer a warm and humid climate at around 80°F (27°C). They perform the best when the temperature is around 80°F (27°C).

Do Mosquitoes Die in Air Conditioned Rooms?

Mosquitoes don’t die in air-conditioned rooms. Mosquitoes become lethargic in an air-conditioned room. Air-conditioned rooms are typically at a temperature around 75°F (24°C). Thus, mosquitoes in air-conditioned rooms do not die but move slowly or don’t move at all.

You may have noticed that mosquitoes are hardly seen in air-conditioned rooms because they were resting or hiding due to the cold environment. Once, you turn off the air conditioner, they are slowly back into action.

Can Air Conditioning Kill Mosquitoes?

You can’t kill mosquitoes with air conditioning. A typical air conditioner can only reach a minimum room temperature of about 68-72°F (20-22°C) which is not sufficient to kill Mosquitoes that die at a temperature of 50°F (10°C). So, you can never kill a mosquito with air conditioning.

However, mosquitoes move slowly or not moving at all when the room temperature is at around 75°F (24°C). Thus, using an air conditioner can stop mosquitoes from disturbing you.

Can Bugs Get In Through Central Air Conditioners?

Bugs can get in through central air conditioners. Bugs can come through the fresh air vent of central air conditioners. However, you can install a screen on the fresh air vent to block bugs and prevent them from entering through central air conditioners into your house.

Bugs are bigger than mosquitoes. Thus, if you have more of a bug problem, you may use plastic mesh instead of metal mesh on the fresh air vent to prevent bugs from getting in through central air conditioners into your house.


Mosquitoes can come through the fresh air vent of air conditioners and the exhaust vent of ventilation fans if we don’t put an insect screen behind the vents. All external vents should have an insect screen as it is a basic requirement for preventing insects and bugs’ intrusion.

Nevertheless, we can solve this annoying issue by either install an insect screen ourselves or replace a new vent with a proper insect screen that lasts for many years.

This article was originally published on Actions will be taken for unauthorised republication of this article.

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Yu Chang Zhen

I enjoy working on air conditioners and ventilation fans because Malaysia is a very hot country.

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