Can Flies Come Through Window Air Conditioners?

For older houses and apartments without central air conditioning units, a window air conditioner is a lifesaver. When you can turn that baby on in the summer and blast away the heat, it can change your life.

When we install a window air conditioner on our house, we are creating a new passage from outside to inside that can be exploited by pests. Insects and bugs like flies will look for weak seals and cracks and try to force their way in. Pretty soon, you could find all manners of pests and insects flying around your room from various holes. No one wants flies inside!

Knowing how and why bugs, pests, and insects, like flies, enter window air conditioning units can help you keep them out for good. Find out how flies come through window air conditioning units, ways to remove them, and solutions to prevent them.

How Can Flies Enter Through Air Conditioning Units

Flies do not go through the air conditioning unit, but rather they find cracks and compromised seals around the AC unit. Often, the unit’s weight settles over time, and new gaps and cracks can be revealed. These holes are quickly found by probing flies that are always searching for food, water, and shelter.

Some insects will follow a water leak and then enter cracks that way. Water, especially in the hot summer, is greatly desired by bugs and insects, and your air conditioner makes a great oasis. Fresh water and the light leaks from our windows are sure to attract bugs throughout all hours.

Can Flies Come Through All Types of Air Conditioning Units

There are different types of air conditioning units, and not all of them are as susceptible to fly infestation as window air conditioners. Let’s look at how alternate air conditioning systems deal with pests.

Types of Air Conditioners

  • Window Air Conditioner – Window air conditioners are installed directly into a window. Often there are gaps, weak seals, and holes in the caulk. Over time insects and flies can work through the caulk and enter your room. Keeping insects out of your room can be challenging with a window air conditioning unit.
  • Central Air Conditioner – These AC units can be sealed very well. The unit outside can have some bug and pest issues and must be kept clean, but it is very unlikely that any insects will make it into your house through the central air conditioning ductwork. Water leaks can present a problem and may result in pest infestations near your central air conditioner.
  • Portable Air Conditioner – These air conditioners can be filled up with water and ice and can produce very cool temperatures. They can be moved around and often only need a small exterior gap to place an exhaust hose out of a window. There can be gaps in the exhaust vent siding, and temporary solutions like regular cardboard or various hardware can keep the cracks sealed tightly.

How to Bug-Proof an Air Conditioner

Finding out why bugs are coming through your AC unit and learning how to bug-proof your window air conditioner is a great way to keep cool air in and unwanted flies out. A window air conditioner doesn’t attract insects on its own but works in combination with other factors to make your home seem like a good option for pests.

5 Things That Attract Bugs to Air Conditioner Units

Window Air Conditioners
  1. Ambient Temperatures – Flies and other insects are sensitive to extreme temperature changes. Most pests would prefer the consistent temperature of our homes during hot summers and frigid winters. Flies will always try to find their way into an inviting temperature climate
  2. Water – Insects need water for a variety of life-supporting functions. Air conditioning units often have leaks that make water readily available to creatures big and small. If this water is allowed to stand and pool, then different insects will take advantage of it. They may also seek the water in your house as well.
  3. Food – The disturbances caused by an air conditioning unit attract insects which are most likely drawn to the vibrations. The more insects around, the more food sources turn up. At the same time, any food sources on the inside of your AC unit will attract pests like flies and ants to make their way into your home.
  4. Shelter – Temperature isn’t the only thing insects need protection from. Air conditioning units can offer shelter and protection from predators and bad weather conditions. Given enough time, desperate insects will find their way inside your house.
  5. Light – If your light is on inside and it is dark outside, bugs will see it. If they see it, they will come, and if there are any gaps or cracks around your window AC unit, they will get in. Make sure everything is sealed, or your lights will attract all sorts of insects.

Remove Bugs From Your Window Air Conditioners By:

  • Clean the outside of the AC unit – Using a wet-dry vac, you can clean the outside of the unit. Suck up all debris and wipe down the unit. Be sure to clean the window air conditioner’s vents and exhausts thoroughly.
  • Inspect for cracks and Gaps – Examine the entire exterior of the window air conditioning unit to make sure there are no holes large enough for insects to enter. Check the hardware and ensure no screws or bolts have fallen out or loosened, creating gaps.
  • Repair, Caulk, Seal – Any Cracks can be filled in and caulked to seal them from insects. Large gaps can be stuffed with cardboard and then caulked to save time and money.
  • Get an air conditioner bug screen – A bug screen can be placed over the exterior vents, which creates a smaller mesh that flies cannot get through. While these screens keep bugs out, they will need to be cleaned frequently to prevent airflow distribution and the AC unit from overheating.
  • Clean up and prevent water leaks – Water leaking around a window unit will attract bugs. If you place a rock garden under the leaking unit, you can trap the water underground where insects are less likely to accumulate. This can solve a leaking AC problem and water some pest-repelling grasses like lemon grass and citronella.

Common Bugs That Come Through Window Air Conditioners

Flies aren’t the only pests that like to make their way into our houses. There are several other bugs that love to use our window air conditioners as a speedy entry point. Check out the table below to see what bugs want in and how to stop them.

PestWhat It WantsHow It Gets InHow to Stop It
FlyFood and WaterThrough gaps around unitCaulk all gaps
CockroachFood/Water/ShelterGaps and cracksSeal and caulk gaps
MosquitoesFood and ShelterThrough vents and ductsVent screens and Repair ductwork
AntsFood/Water/ShelterThrough vents and cracksSeal all gaps and use repellents
SpidersFood/Water/ShelterGaps and cracksSeal all gaps with caulk