Remove the air conditioning vent from the wall or floor area by unscrewing it. Each vent is typically secured with two screws.
Pull the air conditioning vent out of the wall cavity or floor space. The vent has a flush-mount flange that overlaps the drywall and rear flange that tucks inside the sheet-metal ducting.
Measure the dimensions (length and width) of the rear flange that tucks into the sheet-metal ducting. This is the measurement used to size the air conditioning vent.
Purchase a new air conditioning vent from your local home improvement store with the same dimensions as the one you removed.
Slide the rear flange into the metal ducting until the flush mount flange is tight to the wall. Screw the air conditioning vent to the wall with the provided screws.