What Can I Use to Stop Bugs Coming in Through My Window and Air Conditioner?

Your window air conditioner can keep a single room cool, but it can also be a pathway into your home for unwanted critters. Even though the window air conditioner has accordion-style fins on either side to help seal it, these are rarely anything close to airtight. The air conditioner itself has holes large enough to let air through and potentially large enough to let a bug through. Luckily, there are a few things you can do to limit the open spaces for bugs to come in.

Proper installation of the air conditioner is the first step to keeping bugs from crawling in around it. Ensure the air conditioner is seated directly on the window sill, and maintain a slight slope away from the building when viewed from the outside. The top portion of the window should be firmly seated against the top of the air conditioner case, and the vinyl panels on either side of the air conditioner should be extended and secured firmly against the molding. Additionally, make sure you are running your air conditioner with a filter, as this will not only increase the longevity of your unit but can cut down on bugs gaining access to your home.

When a double-hung window is open, there is a gap between the sash of the bottom pane and and the glass of the upper pane. This is a prime entry space for bugs and other vermin. Seal this area using foam air insulation strips and duct tape to clock the gap. You can use colored duct tape to make the job less apparent, and have it match your interior wall color a bit more than the flashy silver stuff.

The vinyl side panels are essentially just sitting against the molding and aren't creating anything resembling an air or bug-tight seal. Use foam applied to the sides of your window to give the vinyl panels a better seal. Apply the foam tape and then expand the panels out so they press against the foam. Secure the panels using the screws they came with when you are done, ensuring you use all of screws provided for a secure closure.

Your double-hung window is designed to form a seal against the windowsill. The window was not designed to seal against the top of an air conditioner, which can leave open gaps that make a perfect entrance for bugs. You can improve the level of air tightness between the window and the air conditioner by laying a thin strip of foam along the top of the air conditioner where the window will press against it.

It can also help to install an L bracket along the top edge of the open window to hold it closed. With the air conditioner positioned correctly and the window closed securely, screw the L bracket in place. Some air conditioners come with the L brackets.