Open the unit and check that the light is on to determine whether the refrigerator is getting power.
Check the temperature setting in the refrigerator portion of the fridge and in the freezer unit and make sure the temperature is set properly.
Move all food away from the vents on the side of the freezer and the refrigerator.
Pull the fridge out from the wall and unplug it. Allow the condenser coils to cool, then vacuum them with a soft vacuum attachment.
Open the door of the fridge and check the gasket (also called the seal) around the door. Inspect it for cracks or worn spots. Replace it by pulling up the gasket slightly to expose the screws. Loosen the screws with a ratchet but do not remove them. Put on the new gasket, starting in the corner, pressing the buttons in all around the door. Tighten the nuts again.
Inspect the drain tube at the bottom of the fridge for clogs. Blow into it with an air hose to remove any debris.