Condenser coils, usually found behind a refrigerator’s kick plate or toe grill, filter air to the cold conductors. When dust, dirt, and pet hair build up on them, the refrigerator may function less efficiently or overheat. Remove or flip up the plate or grill (check your refrigerator’s manual), then use a bottle brush or your vacuum’s brush attachment to gently remove whatever’s caught in the coils. Manufacturers recommend doing this every 6 to 12 months. Cleaning columnist Tara Aronson suggests taking your lifestyle into consideration: If you have an ark’s worth of pets, more often may be appropriate.