Can Bugs Crawl Through Air Conditioners

Bugs can be exceedingly persistent in finding their way indoors. They can easily crawl through small gaps and crevices between windows and floors. Unfortunately, air conditioners are filled with small gaps and crevices as well. So, can bugs crawl through air conditioners?

The answer is yes. However, there are several effective measures you can apply to keep them at bay, including caulking around cracks and crevices and also spraying bug repellants around your unit.

can bugs crawl through air conditioners

In this article, we’ll go over why bugs are often attracted to your air conditioner in the first place. We’ll also go over four tried and tested solutions to keep your AC completely bug-free.

Let’s get started!

Why Bugs Crawl Through Air Conditioners

Bugs are attracted to your unit for a variety of reasons. Below, we’ve compiled three reasons why bugs find their way inside your AC. This will help us better understand how to get rid of them.

They’re Attracted to the Heat

Air conditioners generate heat. This can cause the area around the condenser or on the outside vent to be much warmer than the surroundings. This is why you might notice bugs hovering around your condenser. The cooler temperature in your room may also leak outside, luring bugs indoors.

Finally, some bugs will nest inside your AC or on the outside vent. Bugs nesting will contribute to insect biodiversity in the surroundings. This will ultimately increase the chances of bugs crawling inside.

It’s Getting Too Hot Outdoors

If it’s getting too hot outdoors, most bugs will start actively looking for cooler air. Some pests will seek out the cooler temperatures more than others. This includes cockroaches, centipedes, recluse spiders, and even field mice!

Not all bugs will make their way inside the room. A lot of insects, including mosquitoes and flies, will make their way inside your AC and hang out there. This will provide them with cooler air while enabling them to set up nests where there’s food and shelter.

It’s a Food Source for Bigger Insects

This is where things get pretty disturbing. Since your AC is already attracting a wide variety of bugs, predators will start to appear. 

These predators will set up camp near your AC window, condenser, or outside vent. They’ll attack the bugs nesting there or wait for them to come out. 

Sometimes, bugs are trapped in the AC unit or sucked inside. This is the main reason big predators, like spiders and wasps, make their way inside to feed on the trapped bugs.

How to Bug-Proof Your AC

It seems evident that your AC could harbor a wide variety of insects. So, it’s only logical that a few of them will crawl inside.

Don’t worry, we’ll guide you through four proven methods that will ensure that insects are kept at bay.  

Fill in the Cracks

Any cracks around your AC will cause bugs to make their way inside. Even hairline crevices should be patched up. There are two ways you can do this.

Duct Tape

Duck Max Strength 240867 Duct Tape, 1-Pack 1.88 Inch x 35 Yard Black

Duct tape is perhaps the most popular option to fix just about everything. If you have any visible cracks, hairline crevices, or small holes, using duct tape will effectively seal up the area.

However, there are a few downsides to using duct tape. For instance, gaps that are wider than one inch won’t be properly sealed by duct tape. 

Even for smaller cracks, duct tape doesn’t provide proper insulation like other fillers. This will make your AC run for longer, and will ultimately rack up your electricity bill.

Overall, duct tapes are easier to apply, easier to remove, and are the more convenient option for small cracks.

Rope Caulk

Frost King F4 Mortite Caulking Cord 9-1/2-ounce 45-Feet Long, Grey, 9-1/2 oz, ft, Gray

Caulk is a much better option for wider gaps and big cracks. There are several different types of caulk, but we recommend rope caulk the most.

Rope caulk easily molds to the surface, allowing for better sealing for the larger cracks. It also has better insulation than duct tape, which means your AC will run a little bit more efficiently.

All you need to do is buy an applicator gun, apply the seal to the cracks, and finish up with the rope caulk.

Prevent Water Leaks

Do you have any water leaks from the condenser or inside your room? You need to fix that immediately.

Water offers a damp environment that suits a lot of insects. Cockroaches, for example, will quickly infest the damp area around the condenser or make their way into your room if water leaks inside.

To avoid that, it’s best to schedule an AC tune-up to inspect the water leak. Water leaks are not only a beacon for bugs, they also indicate a problem with your AC.

Clean the Condenser

This extends to the AC unit itself. However, the main cause of bug infestation is usually a dirty condenser.

First, turn off the power to the condenser unit. Use a vacuum to clean the debris. If you can remove the fan, clean the fins with water and reinstall the fan.

For the AC unit itself, remove the filters and clean them with water. Make sure they’re completely dry before reinstalling.

Spray Bug Repellents

Ortho Home Defense Insect Killer for Indoor & Perimeter2: With Comfort Wand, Kills Ants, Cockroaches, Spiders, Fleas & Ticks, Odor Free, 1.1 gal.

Finally, bug repellents are incredibly effective at keeping bugs away from your unit. Avoid spraying insecticides directly inside the unit, as the chemicals will circulate in the room. Instead, choose natural bug repellents made with essential oils.

You can also use a DEET bug repellent outside your window AC and around the condenser. This will force the bugs to avoid the whole area entirely.

The only limitation of spraying bug repellents is their lasting effect. You’ll need to spray the unit and around the condenser two or three times a week. Also, spraying bug repellents when you have a dirty condenser, cracks, and water leaks will barely yield any results.


If you followed our guide carefully, you’re now equipped with several effective solutions to keep these annoying bugs away from your room.

Remember, there’s no magical solution to completely eradicate all bugs. If you want to stop the bugs from crawling through, take some time to assess the situation, then apply the appropriate measure(s) from our list.

Are bugs still crawling through your AC? Maybe it’s time to call a pest control service.

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