Informational Guide

How To Stop Bugs From Coming Through Air Conditioner Vents

AC vents are a known hiding place for a variety of insects, including spiders, bed bugs, and cockroaches, as well as bigger pests such as mice, rats, and snakes.

by Josh M

Do you have bugs coming in through the air conditioner vents and terrorizing your home? AC vents are a known hiding place for a variety of insects, including spiders, bed bugs, and cockroaches, as well as bigger pests such as mice, rats, and snakes. In this guide, we will show you how to prevent bugs from coming through air conditioner vents and how to keep your clean free from infestations.

Install Screen On Air Vents

If you install a screen on all external air vents, you will prevent bugs from coming in through the air vent. Most bugs enter the air vents from outside your home, not inside your home. Installing screens on each external air vent can prevent critters from coming in.

We recommend an aluminum wire mesh because they are both strong and lightweight. You should be able to easily install these screen vents on your own, but a handyman can also install them for you without difficulty.

Clean The Central Air Conditioner

Bugs love dirty, moist, and dark places. If you do not regularly clean your central air conditioner, bugs will be more than happy to climb inside and make their way into your home.

We recommend cleaning your central air conditioner unit every six months. Thoroughly wipe down the exterior and make sure that you wipe down the air duct as well. Every 3 to 5 years, we recommend hiring a professional to perform an air duct cleaning by blowing out old dirt and debris. This will discourage bugs from coming inside.

Seal The Ductwork

Over time, air conditioner units break down in the same way that other appliances break down. Any leaks or holes in the ductwork of your AC unit will lead to excess moisture and an opening for bugs to crawl through.

We recommend reviewing your ductwork and sealing any areas where cracks, holes, or leaks are found.

Fill in the Holes

If you have holes in your AC unit, whether these holes are in the ductwork or the air vent, you need to fill in the holes. If you have holes in your home’s exterior around the vent, this can also be a problem.

Make sure that the external air vent is sealed on all sides. Bugs love to climb into AC systems through the cracks, whether within the unit itself or outside the unit around the edge of the vent.

How To Get Rid Of Bugs Inside Air Conditioner Systems

It is always easier to keep bugs out of your AC system and prevent their entry than deal with them after they have arrived. However, if bugs have already made their way into your AC system, it’s time to get them out without the use of pesticides. Using pesticides is dangerous and can make everyone sick in your home.

When bugs are inside your air conditioner, you might notice it by seeing staining around your AC vent (red, brown, or black dots or crusty streaks). You also might notice that bugs are present in the AC system because of how many more bugs are in your home. Do you all of a sudden have a lot of flies and other insects flying around?

Seeing an unusually large number of spiders? They could be coming from the AC unit. If you do not remove the bugs from the unit, they can cause damage. Some insects that try to enter your home will end up dying in the vents and can create airflow problems, damage fan blades, and may attract more bugs.

The first step when getting rid of bugs in your air conditioner is to turn off the AC system. Turn off the thermostat, then shut off the power switch. The next step is to clean any debris or dirt that you find outside around your AC unit. Remove leaves, dirt, and anything else that can be seen around the machine.

From here, you want to take the exterior vent grill off of the machine. You will need to unscrew the grill.

The second step is to clean the machine using a wet vac. We recommend renting one from your local hardware store if you do not have one. Use only the air around the evaporator coils (no moisture). Then, use a gentle soap and clean the ducts as well as you can but make sure to once again avoid the evaporator coils.

Finally, put the external air vent back on your AC machine. Screw it into place. Now add an aluminum wire mesh piece to the outside of the grill and make sure that it is securely connected to the grill. Turn the unit back on. Conduct regular inspections of your AC unit to make sure that there are no bugs, insects, or other pests starting to return.

Split Air Conditioner on House Roof

How Do Bugs Get Into Air Conditioners?

Bugs get into air conditioner units through two primary avenues: vents and ducts. Most insects and bugs enjoy damp, dark ac vents with mold and dirt in them. If you have not maintained your air conditioner unit and kept it clean and dry, bugs will want to find their way in.

Even if you do maintain your unit, bugs can come in through the vents by finding small spaces and sneaking in. The place where we see bugs come in the most is through the air vent in your AC/HVAC unit. Another way that bugs can get in is by moving through the air ducts. If your air ducts have cracks or loose seals, bugs will attempt to make their way into your home.

Ants and Insects Walking in a File

What Kind of Bugs Can Get Through My AC Vents?

We often have clients who ask us,

“What are the most common bugs that get into AC vents?”

The most common bugs that we find in our client’s homes who came in through the AC vent would be spiders, ants, mosquitoes, bed bugs, roaches, and flies. We also see bigger pests such as snakes, mice, and rats. These insects and pests get in the same way: through the ducts and vents in AC systems.

“Can mosquitoes come through air conditioner?”

Yes, unfortunately, mosquitoes can come in through your air conditioner. Mosquitoes are small insects that fly, and if you have any open cracks or extra space in your vent, mosquitoes will be very interested in making their way into your home. You need to take inventory of your AC system and make sure that every crack and open area is completely sealed off.

People Also Ask (FAQ)

Can I spray bug spray in air vents?

No, you should not spray pesticides in your AC vents. If you spray pesticide in these vents, whenever the AC unit comes on, pesticide fumes will move throughout the home and make everyone sick. This can be dangerous. Pesticide use in your air vents is not the answer.

Can spiders come through air vents?

Yes, spiders can come through air vents. Most spiders are agile enough to find their way into the air vent as well as maneuver around it. Spiders can also find their way into your home through cables, plumbing lines, pipes, and entrance gaps such as cracks in your doors or windows.

How do I keep roaches out of my vents?

One of the simplest ways to keep roaches out of your air vents is by closing off all access to your vents with mesh screens covering the external vent entrance. Aluminum wire mesh is strong yet lightweight and can easily be placed over your vents to keep roaches out.

Can drain flies come through air vents?

Yes, drain flies can come through air vents and invade your home. Drain flies tend to show up when there is either damp soil outside near the air vent exhaust system, or there is a leak in one of the plumbing lines. Drain flies like damp spaces and tends to congregate near them.


In order to stop bugs from coming in through your air conditioner vents, we recommend sealing and fixing any cracks or leaks in your AC ductwork, as well as cleaning your AC unit thoroughly. Then, we recommend adding aluminum wire mesh to the exterior of each vent. This will secure your vents and keep annoying pests out.

Last Updated on May 26, 2022

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.