How to Install Air Conditioner Weather Seals

Open the window in which you plan to install the air conditioner. Clean all parts of the window frame where you plan to install weather seal and allow it to dry completely. Measure the bottom side of the open window with the tape measure.

Cut a piece of weather seal that is the same length of the window bottom with the scissors. Pull the back off of the weather seal and press the sticky part against the underside of the window, until it stays in place.

Measure the windowsill with the tape measure and cut a piece of seal that's the same length with scissors. Pull the back off of the weather seal and press the seal, sticky side down, to the windowsill.

Measure the length of the left and right side of the inner, open window frame. Cut two weather seal strips for each side of the frame, peel off the backside of the weather seal and press the pieces of weather seal against the left and right side of the window frame until they stick.

Install the unit into the window and properly lock down the open window. Pull the accordion-like panels to the sides of the window frame and screw them securely into place. Confirm that the unit is snugly tucked against the weather seal and that there are no gaps where air can escape.

Measure the top of the open window with the tape measure and cut a piece of weather seal that's the same length. Peel the back off of the weather seal strip and apply it to the opening between the stationary window and the open window to block the air from flowing through the gap.

Inspect the remaining area around the air conditioner. If you see holes or areas where air can escape, cut weather seal strips the size of the gaps and plug them up.