Use the drill with the screwdriver bit to remove the screws that holds each vent in place. Put the screws in a safe place, so they don't get lost. Keep each cover's set of screws separate from the other screws because, sometimes, the screws from one vent cover won't properly fit another cover.
Sand each vent cover to remove peeling paint, scratches or bubbles. Do not use a medium- or heavy-grit sandpaper as it will create new scratches with will be visible when the vents are painted.
Wipe the sanded vents with a tack cloth. If needed, use a mild solution of dishwashing liquid and water to clean stubborn spots. Dry thoroughly with a clean cloth.
Lay newspapers down on your work surface and place the vent covers upside down on it. Work in a well-ventilated workshop or outside to protect yourself against paint fumes.
Hold the paint can 10 to 12 inches away from the vent cover and, spray a thin layer of paint to the back of the vent. Apply an even coat of paint by moving the can back and forth as you work; this will avoid drips and dark spots. Allow to dry for two hours.
Turn the vent cover over and set it on a clean area of newspaper. Again, spray on an even coat of paint. Allow each vent cover to dry for 4 hours.
Replace the vent covers and screw them into position.