Extension Special Series No. 11D
A refrigerator must be level for best operation so you should check to make sure your appliance is level. For best results the appliance should be placed away from a range, radiator, water heater sunny window, or other source of heat. The appliance must also be in a location that does not become too cold. The heat or extreme cold will cause the motor to work too much or not enough and then the interior temperature of the appliance will not be correct.
South Dakota State University
Service, Cooperative Extension, "A Clean Refrigerator" (1970). SDSU Extension Special Series. 101.