How to get rid of pests portable AC.

How to Prevent Bugs from Coming Through Air Conditioner (Bats, Mosquitoes, and More!)

So, you have bugs in your air conditioner and you need to get rid of them.

In this comprehensive tutorial, you’ll learn:

  • Why bugs are in your AC unit
  • How to stop bugs from entering your room through your window air conditioner
  • Ways to keep bugs out of your room through your AC
  • And more

By the end of it, you’ll have everything you need to know to stop annoying bugs keeping you up at night.

Feel free to bookmark this page so you can come back easily if needed.

Sound good? Let’s clean up your AC unit!

Can bugs come through a portable air conditioner?

Windows on homes are easy targets for pests
Bugs in your window AC? Get rid of them.

Yes, they definitely can and will.

The main reason why bugs are in your AC unit is that no seal is airtight.

There’s always a small crevice or gap between the portable air conditioner and the window- even if you can’t see it.

Unless you’ve sealed it, small bugs can easily find their way through the unit into your room. They can enter the AC unit directly and come out the other end, or they squeeze through the edges of the unit because it’s not flush against your window frame.

Some portable units have the accordion stretch panels, but even then, there are still small cracks.

These units are rarely airtight. Spiders, bats, and mosquitoes are common pests that sneak into homes through the window AC. Even though most units are set up correctly, sometimes pests can still break through the barrier.

Other times, it’s because of the device itself has no vent to block off the outside pests from nesting inside the unit or using git as a bridge into your home. Because of this, you need to first assess the issue at hand:

How are the bugs coming into your room?

Ask yourself these questions:

  • Are they coming in from the gaps surrounding the window unit?
  • Or are they coming in through the actual unit?

These are important questions because it’ll let you know where the problem lies.

You may need a new AC unit if they keep getting inside it. Or you may just need to do some housework and create a seal around your air conditioning. This could save you time and money.

Why are bugs coming into my room from my window?

Mosquito air conditioning.
Bugs are attracted to food, light, and shelter.

Bugs are attracted to many different things in your room, such as light, shelter, temperature, and food.

Depending on where you live, the temperature in your house is probably a lot nicer than the temperature outdoors.

So that’s why bugs find their way through your AC unit into your room. If it’s too cold or hot outside, the temperature in your room is a lot more attractive to them, so they’re drawn to your room.

Combine that with the fact that the warmth or coolness of your room “leaks” through the AC unit to the outdoors, they can sense this and are lured to your room.

Bugs like light

Also, light is another major attractant of spiders, flies, and other nighttime pests. If you have a portable air conditioner on your window and you keep your lights on at night, these bugs will naturally be drawn to your room.

You can try to reduce the light pollution by using blinds, covers, or something else to block your window from the outdoors during the night, but this isn’t always practical.

Availability of food

Food is another attractant. If you have a steady source of pests in your air conditioning unit, room, or house, other bugs will be trying to get into your home.

This is especially true if you have bugs living in your air conditioner unit because other bugs that prey on them will constantly be scavenging for food to eat.

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Thus, they’ll hang around your AC unit and eventually find their way into your home.

As you can see, there are many different reasons why you have bugs coming into your room from your air conditioner. There’s no specific reason, it’s usually a combination of all of temperature, light, and food.

You can eliminate some of them, such as using blinds or cleaning out your AC to help reduce the number of bugs coming into your home. But this isn’t guaranteed to do anything at all. It’s best to use some kind of sealants such as caulk, paper towels, duck tape, or even construction paper to seal up all the possible crevices.

This will actually stop the majority of the bugs from getting into your home.

Air conditioner insects

There are many bugs that’ll hang around your window AC unit, and some will even live inside your air conditioner!

The most common bugs are mosquitoes, flies (cluster flies, lanternflies, and mayflies), spiders, and cockroaches.

Why do I have bugs in my air conditioner?

They don’t just nest inside your AC for no reason. There are two main reasons why bugs are in your AC unit: Food and shelter.

Air conditioner units create a suitable habitat for a few reasons.

Heat and shelter

The appliance generates heat, which some bugs are attracted to and will end up nesting on the outside vent or on the inside of your AC. Other bugs will just be attracted to the heat and hover around the unit to keep warm.

Bats have also been reported to hang around them. The AC also provides an area for predators to eat bugs because it “sucks” air in, which collects and traps a lot of small bugs.

Window AC units can be a food source

Some predators will hang around the window unit waiting for bugs or will live inside the air conditioner to eat trapped bugs that were sucked into it.

This is pretty disturbing, but at the same time, this is why you need to stop bugs from entering your AC in the first place.

Do bugs like air conditioning?

Most bugs will appreciate the cooler air especially if it’s hot outdoors.

Some pests like cockroaches, field mice, recluse spiders, and even centipedes will seek out more preferable temperatures inside your home.

If the outdoors is too hot, bugs will naturally migrate to where temperatures are cooler. If you have the AC running, they’ll find a way to get into your home because they’re attracted to the cooler air.

How to stop bugs coming in from the AC

Moth outdoors.
Here are some tips to help you prevent these bugs.

There are multiple ways to do this, but here are the proven methods that have decent success rates.

Depending on your air conditioning setup, not all of these methods will apply to you. So choose the one that best fits your situation.

Use duct tape

Duct tape fixes everything. And AC units are no exception.

You can use duct tape to quickly seal up any visible cracks around the unit and your window. If you have hairline crevices, duct tape is an easy solution that’s cheap, fast, and does the job.

Duct tape doesn’t work for any gaps that are wider than an inch thick. And even then, you’re pushing your chances. Duct tape should only be used to seal up small cracks.

Larger ones will require more extreme measures. Keep in mind that duct tape doesn’t hold insulation well, so you’ll end up running your AC or heating up which will cost you more dollars in electricity.

Caulk up the gaps

Caulk is the next best option. There are many different types of caulk on the market, but you can use basic cheap caulk with an applicator to hold a seal.

You’ll want to get one that’s safe for wood and used for basic sealing so you can remove it easily in the future.

There are many grades of caulk, do you research or ask an associate for help at any hardware store. You’re just looking for something that’s easily moldable and removable.

Rope caulk

Rope caulk is a good example. It’s basically a sticky putty that you can easily mold like Play-Doh and seal up the cracks.

You can buy it at most hardware stores for cheap. This works best for gaps between your AC and the cracks above or below the unit on the windowsill and top window.

Duct tape vs. caulk

For gaps that the accordion side panels don’t seal, consider using duct tape instead of caulk. It’s much easier to remove in the future and also to adjust the accordion panels. If you seal it up with caulk and need to adjust later, it’s a pain.

So using duct tape is easier and more convenient for horizontal panels.

Most AC units have some kind of extenders to fit flush into your window frame to keep bugs out. Seal off the edges completely with duct tape to make it more secure against flying bugs and spiders.

No seal is airtight.

Use screening

You can use window screening on the outside of your AC to block pests from coming in.

Even if your air conditioning doesn’t fit flush against your window, the screen covering the entire window blocks any mosquitoes, spiders, or other flying pests from entering your room.

This is the all-out approach that works best, but it requires that you install the screening correctly in the first place. If you install it poorly, there will be a bunch of gaps that the bugs will use to enter your room.

This is one of the most effective and best ways to seal a window air conditioner.

If your air conditioning “hangs” outward, you can use additional screening to give it some wiggle room.

This can accommodate your unit even if it juts out. Installing window screening is very easy and will help prevent the majority of pests from coming into your room through your air conditioning.

Here’s a tutorial that explains the process.

Use cardboard

If you have an A/C unit that uses accordion flaps, you can cut up regular cardboard that fits perfectly to seal up every single hole.

You can tape the cardboard around your window. Make sure you cover all the edges and cracks as even the tiniest entry point will be used by bugs.

Sure, it’s not pretty and it’s a lot of work. But what do you expect? These bugs don’t know any better. This is one of the cheapest ways to seal a window air conditioner.

Use paper towels

You can fold up thick paper towels into rolls and stuff them into the cracks around your AC unit.

There are gaps on the top and sides were paper towels will fit nicely. You can shove multiple paper towels into each gap until it’s completely tight.

Buy a bunch of towels in bulk and shape them to your AC unit and window. You can also use duct tape to secure the paper towels in place.

Use a different room

You can always move your portal unit to another room or window.

An alternate room may have fewer bugs, or it shouldn’t bother you as much if the bugs are entering from somewhere else. At least it’s not your room.

Block off that room from your room. Add traps, bug lights, or citronella candles in that room to repel pests from coming in through the window.

Think of it as a quarantine room for bugs that happen to get in, but stops them before they reach you at night. Especially when you’re sleeping.

Mosquitoes coming through the window air conditioner

If you have mosquitoes entering your room through your AC, this is likely because of the temperature of your room.

Mosquitoes are attracted to temperatures around 80 degrees and above. They prefer warmer temperatures.

And if your room has this, they’ll naturally try to find their way in. If you have cracks around your seal on your window, then this is how they’re getting into your room.

Since they’re relatively small flying pests, they can squeeze through the smallest cracks in search of prey to draw blood from.

They can detect human breath from afar, so if you’re spending a lot of time in your room, chances are that your CO2 is leaving the room through the window. And this attracts mosquitoes. If they’re coming in through the cracks, your options are to seal it up by caulking or duct tape.

Or if they’re coming into your home through the actual AC unit, then you need to seal up the outer vent. Or add a window screen on the outside. You don’t want mosquitoes at night, this will drive you crazy and poses a health risk.

You should block them off from possible entry into your room as soon as you notice the problem. Consult a professional and ask for an opinion if you’re lost.

Can spiders get in through air conditioner?

Yes, spiders can easily get into your home through your window air conditioning system. If you don’t have a fully-enclosed seal that’s flush against your window frame, then spiders can sneak through the poorly setup blockade.

Or if you have an older model, it may not be equipped with the vents to block bugs from coming in from the outdoors.

You need to upgrade to a newer model or use window screening in this case. The first step is to establish where and how the spiders are coming in.

Are they coming in from the miniature crevices surrounding the AC? Or are they coming in from the unit itself?

After that, assess the situation and decide if you need to just install some insulation around the device if you need to buy a new one altogether.

Do bed bugs live in window air conditioners?

Probably not. Bed bugs can’t stand temperatures that are too cold or too hot.

They also don’t like strong airflow and prefer stagnant air. If you have bed bugs inside your air conditioner, you’ll want to double-check to make sure you actually have them.

The strong airflow created by the AC unit often disturbs bed bugs from nesting inside it, and thus prevents them from living inside the unit. It also creates a lot of cold and hot air depending on what part of the unit they’re investing in (compressor, fan, electrical, pump, etc.).

Bed bugs also don’t like moving air, and AC units are made to move air. So the chances of them nesting in your air conditioner is rare. Unless you never use it. Then it’s a possibility and you may want to clean it out.

Can bats get in through window air conditioners?

Bat outside on tree.
Bats are no stranger to air conditioner units.

Yes, bats can definitely come in through cracks around your AC window unit.

Bats are attracted to the strong airflow that leaks from your room and will hover around the AC unit until they find a way through. You may even catch the bat right up against the window.

They bat typically will fly onto the AC unit and crawl between the glass panes until they can squeeze their way through.

Use strong lights as a bat repellent

Bats tend to avoid strong lights, so you could try removing your blinds to let more light through to the outdoors.

But you may end up risking more pests that ARE attracted to lights by doing this. Bats will try to break through the barriers you set up to get into your home.

Bat proof your window air conditioner

They use airflow to navigate and the AC creates an artificial flight path for them. You can prevent them from getting into your home by using a piece of foam shaped in a tube.

They bat climbs through the gap between your two panes, so you need to shove a foam piece between the two glass panes. Make sure the adjustable extenders are flush against the wall on both sides.

You can caulk, tape, or even use screws to secure the accordion extenders to the fame. This will help prevent bats from getting through. You can screen the entire outdoors as a last resort.

Note that if you already have a bat problem in your home, you should take care of it rather than use a temporary solution.

Stop bugs from coming through window ac

Stopping bugs entering your home is done in two ways. One is sealing up the edges around your AC unit and window.

The other is to make sure no bugs can enter through your window AC, which means it’s up to the model you have. Most have some kind of mechanism that allows you to shut your AC’s outside air vent to block the entry of pests.

But if you don’t have this and your window unit is just a bridge for bugs to enter your room, then you need to either use window screening on the outside or buy a new AC unit.

There’s really no other way to stop them from entering through the AC. Most units have built-in filters and parts that make it hard for bugs to enter. And they have an outside vent that can be shut. So using these should make the process easier.

How to bug-proof your window AC

The best way to bug-proof your window AC is to use a combination of duct tape, cardboard, and caulking to insulate it against any pests.

Most units already have extendable flaps on the sides to stretch out horizontally, but they rarely are flush against your window’s frame.

This is why you need to assess the situation and see the best approach.

Duct tape is best for small cracks (1-inch max). Caulk is best for tiny cracks that you want to seal up permanently. Cardboard can be used for void fill. As you can see, you’ll have to use a combo of different pieces to completely seal it off.

For a long-term solution, such as the part of the window that meets your air conditioner (top part), use caulk and cardboard.

For the sides, use tape so you can easily remove it if you need to adjust later.

Did you stop the bugs?

Pest free AC.
Did you clean up your AC?

By now, you have everything you need to know to make some moves. Go ahead and get started.

Assess your situation and choose whatever methods here work best for you. No single solution “fits all.”

If you have any questions, leave a reply below and I’ll get back to you ASAP!

And if you found this page to be helpful, let me know. Consider telling a friend =].

Thanks for reading on BugWiz!

5 thoughts on “How to Prevent Bugs from Coming Through Air Conditioner (Bats, Mosquitoes, and More!)”

  1. These are good suggestions for people that are either broke, in college, or looking for a half-assed solution. There are only a few things that actually work.

    1. Start by spraying the exterior wall and ground with Ortho Home Defense. Can use on interior window sills as well. Clean the windows and use vinegar/water solution after the bug spray dries.

    2. Make sure the window screens are installed properly and have no holes.

    3. Tape excess window screen to the exterior and interior vents. Buy screen at home depot for $10 a roll. Try to get the cheaper black or grey kind, as the silver sunscreen option is too heavy for this use. There is a large exterior vent on the A/C backing which needs to remain open, but make sure you tape all other vents including INTERIOR VENTS. This is where 90% of the bugs get in

    4. Make sure the window A/C unit is clean and installed properly.
    -this includes making sure the accordion portion is flush with the window and nailed tight
    -this includes making sure that the A/C is at a downward angle so water doesn’t collect and attract bugs

    5. Seal the top space in between window panes with self-adhesive foam. Maybe $5 at home depot (bugs will try again and again to get through so make sure this is done well)

    6. Gaps will typically occur under the window A/C unit even when installed properly. Measure the length and height of the gap. The plan is to nail board across the width of the window, covering the gap. You can measure depth too but not as important. Get a home improvement store to cut MDF wood (about $6) or real wood into the measurement. Buy 1-1/2 inch screws or nails and hammer the board in. You can also prime and paint the wood to match the trim.

    7. Caulk the interior. Watch youtube videos if you are unsure how to do this, but its pretty easy

    8. Make sure to review your work in daylight in case gaps still exist. As each summer passes, you will see improvement in your work. Waterproof tape is not the only option either, so explore what might work for you. If you really want a professional look, spraypaint the roll of window screen to match the color of your A/C.

    9. As an additional measure, you can also buy a self-adhesive or magnetic interior and exterior bug screen that completely encompasses the windowframe. Keep your light off at night, blinds closed, dim electronics, don’t keep soda cans or food on the windowsill, and don’t smoke. Everything mentioned will attract bugs.

    10. Check to make sure no gaps exist as the season progresses. The steps mentioned will solve 99.99% of bug issues as it relates to the A/C. You could still have other issues in your home or wall cracks that let in bugs. If you see spiders, that means you have bugs.

  2. Benjamin Brackman

    I sealed around my window air conditioner with thick plastic (the plastic used to cover windows, folded over twice) and clear duct tape both on the inside of the window, and on the outside of the window, and we have no mosquitos or other bugs of any kind getting in to my apartment .

  3. Benjamin Brackman

    I sealed around my window air conditioner with thick plastic (the plastic used to cover windows, folded over twice) and clear duct tape both on the inside of the window, and on the outside of the window, and we have no mosquitos or other bugs of any kind getting in to my apartment .

  4. The information you gave about mosquitos and how they can travel through air conditioners because of the warm temperatures really helped to read. Mosquitos have been the number one thing my neighbors have warned me about ever since I moved into my new house, and I want to take their advice seriously so my kids won’t get sick. With how warm it can get here sometimes, I’m definitely going to take some extra measures against them, so I’ll find better ways to use my air conditioning unit after getting a pest control service to help me pest-proof the place.

  5. There should be a distinction between mosquitos entering through the AC and mosquitos entering through gaps in the area of the AC. The fins behind window AC units (a storm recently disabled my central unit & I’m using window units till repairs) exhaust heat while ports on the sides and top allow air into the unit to cause evaporation and condensation of the coolant. Mosquitos by the gazillions enter the unit and somehow find their way into the house. In addition, they die in the heat exchange fins and cause a horrible stench outside. I’m currently fashioning screen material to make it impossible for mosquitos to enter the unit, so that they can’t find their way to the blower that pushes cold air into the house. We’ll see.

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