Wet a dishrag and put a couple drops of dish soap on it. Get it lathery and wring it out. Clean the dented area. Rinse the rag and wipe the dented area to remove soapy residue. Dry the appliance with a dish towel.
Plug in a hair dryer and have your compressed air ready. Turn the hair dryer on at the hottest setting. Move the nozzle back and forth across the dented area for 30 seconds to one minute, depending on the severity of the dent.
Spray the dent for 10 seconds while holding the canister upside down so that the bottom of the canister is level with the ceiling. This releases liquid carbon dioxide.
Give the temperature difference between the heated appliance and the liquid carbon dioxide time to force out the dent. If the dent does not pop out in three minutes, repeat the process, heating the dent for a longer period of time, up to one minute and 30 seconds. Spray the dent with liquid carbon dioxide for 15 seconds.
Wipe off any remaining residue with a damp dishrag, and dry the appliance with a clean dish towel.