Condenser coils
The dusty coils on your fridge (and AC) that shed heat — keep them clean.
Condenser coils release the heat your refrigerator or air conditioner removes. When they're coated in dust and pet hair, the system runs hotter, works harder, and wears out years early. Vacuuming the fridge coils once or twice a year is one of the cheapest appliance-life extenders there is.