Homemade AC Filter

Remove the screws from around the air conditioner's grille using a Phillips screwdriver or a Torx screwdriver (depending on the make of the AC unit). The grille is typically on one side of the air conditioner module that is outside the home, against one of the walls. Place the screws in your pocket for safekeeping.

Pull the grille off the AC unit. Wipe off the inside and outside of the grille with water-moistened paper towels. Place the grille aside. Grip a corner of the filter frame that is inside the compartment the grille was covering with your hands. Pull the filter frame out.

Place the filter frame on a work surface. Cut through the inside edges of the filter frame, using the blade of a utility knife. Pull the filter material out from the frame.

Measure the length and width of the cut-out filter. Write these measurement down. Dispose of the filter material properly (in the trash if the filter is made of a disposable material, and at a recycling center if the filter is made of a metal mesh material).

Cut a sheet of fine-mesh screening material that matches the width of the filter to the dimensions that you wrote down, using a utility knife and a straight edge. Dispose of the cut-off pieces in the trash.

Apply bonding glue to the inside edges of the filter frame. Place the homemade filter into the filter frame. Press all of the sides of the filter against the frame so that the glue adheres the two together. Let the glue set for three hours.

Place your homemade filter in the compartment so that it is in the same position as the original filter was. Place the grille on the compartment. Reattach the screws.