Adjust the ac unit s window vent panel to extend across the width of the opening.
How to properly seal a window ac unit.
Flashing tape is the first line of defense.
Narrow or hard to reach gaps measure the length of gaps that are 1 8 inch thick or smaller.
Measure the width of the windowsill and use a pencil to mark.
Ask a helper to hold the air conditioner unit in place while you raise the bottom window sash up enough so that you can access the bottom edge.
Before installing a window ac open the window as far as it goes remove the screen and clean the windowsill glass and window frame.
Smooth the caulk and wipe away.
Cut foam weather stripping to length and attach to the window sash and frame.
Then lift the window and place the seal under the lip of the window.
Re close the window tightly.
If the gap is deep you may need to press two pieces into the gap to fill it completely.
Tear off a length of rope caulk to match.
Step 3 examine the sash.
Then fold down the house wrap at the top and cover the diagonal slits at the top with house wrap tape.
Most window air conditioners come with an accordion style flap attached to the sides to fill the open space.
Open the window where the portable air conditioner will be located.
Seal around the window with flashing tape lapping the top piece over the sides.
2 position the end of the weatherstripping at one end.