How to prevent rain from coming in around window air conditioners

Updated March 23, 2017

Window air conditioning units provide cool air to interior rooms. Unfortunately, some window air conditioners develop leaks around them when it rains. Finding out why rain is coming in around a window air conditioner and fixing the problem can require you to inspect both the inside and outside of the window to pinpoint the problem. Most leaks can be repaired in a short amount of time.

Check the air conditioner and make sure that it is properly installed. Make sure that the accordion panels on each side of the air conditioner are fully extended and secured to the window frame and that the window pane itself is lowered into the bracket on top of the air conditioner. Adjust the panels or the window pane to close any visible gaps.

Inspect the accordion panels for holes, tears or signs of wear that may indicate leaks. Check for debris that may have pushed the panels out of their tracks, creating a small space where rain can leak through. Look on both the inside and outside of the house when checking the panels for holes.

Look for signs of water damage on the window frame itself or other indications that the leak might come from the window and not the air conditioner. If possible, try to pinpoint the exact location of the leak if you notice it while it's raining outside. If you can't find the leak when it's raining, look for discolouration, dampness, or other water damage to find the leak's location.

Seal holes in the accordion panels or window frame with caulking or silicon sealant. If the leaks are caused by excessive damage to one or both of the accordion panels, you may have to replace the panels by ordering replacement parts from the air conditioner manufacturer or installing makeshift panels made of wood or other materials.


Sealing leaks that allow water into your home can also stop air leaks that cost you money on your heating and cooling bills.

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About the Author

Born in West Virginia, Jack Gerard now lives in Kentucky. A writer and editor with more than 10 years of experience, he has written both articles and poetry for publication in magazines and online. A former nationally ranked sport fencer, Gerard also spent several years as a fencing coach and trainer.