Check the door seals. A loose seal allows cool air to seep out.This is not only an enery waster but it makes your fridge work a lot harder than necessary. First make sure the seals are free of food residue. (Clean them about twice a year, using a toothbrush and a solution of baking soda and water.) Then try the dollar-bill test: Close the bill in the door so that half is in and half is out. If it slips out easily, you may need to have the door seals checked by a pro.
Keep the coils clean. When the condenser coils (see following page for more on parts) are covered with dust, the refrigerator can’t run efficiently. Twice a year, pull the machine from the wall to reveal the coils in back (or snap off the grille, if the coils are on the bottom front), unplug the refrigerator, and vacuum using the brush attachment.
Set the right temperature. Keep the fridge between 37 and 40 degrees Fahrenheit and the freezer at 0 degrees.