Empty the dishwasher of dishes. Leave the door open and allow the inside of the dishwasher to cool completely.
Fill a plastic zip bag with ice cubes. Lay the ice bag on top of the melted plastic stuck to the heating coils. Leave the bag in place for 30 to 60 minutes, until the plastic is hard.
Remove the ice bag from the heating coils. Carefully scrape the hardened plastic off the heating coils with a razor-edged scraper. Discard the plastic bits and continue to scrape off the plastic to get as close to the coils as possible.
Wet a clean cloth with acetone-based nail polish remover. Lay the cloth over the remaining melted plastic residue on the dishwasher heating coils. Leave the cloth in place for five minutes to dissolve the plastic.
Scrub the coils with the remover-soaked cloth to remove the residue. Rinse the coils with a damp cloth.
Wet a cloth with warm water. Add two drops of dishwashing detergent. Clean the heating coils to remove any remaining melted plastic residue and nail polish remover.