Routine maintenance is important for refrigerators. Dirt should be cleaned from the refrigerator coils every six months to a year – more often if there are shedding pets in the home.
When coils are dirty with lint, dust, or pet hair, the refrigerator has to work harder than it’s designed to, which can prevent the appliance from cooling properly and efficiently. This can increase the energy cost of the refrigerator by as much as 35% and shortens the life of the refrigerator.
Also, keep the refrigerator or freezer away from direct heat. Place the refrigerator or freezer away from direct sunlight and other heat sources such as ovens or ranges. Heat will cause the unit to use more energy to stay cold.
Do not forget to regularly change the water filter, if the refrigerator has an in-the-door ice and water dispenser, and the air filter which now come with many models.
https://www.energy.gov/energysaver/purchasing-and-maintaining-refrigerators-and-freezers