Because of the location of the motor, the back of a refrigerator typically feels warmer than the sides or the front. But if the rear exterior surface radiates a large amount of heat, the motor may be running too hot. Consider calling a repairman to fix any fridge less than six or eight years old (especially if it’s under warranty). If the appliance is older, however, it's probably best to replace it. After all, repairing a malfunctioning motor can cost hundreds of dollars, and you're likely to need a new fridge soon anyway.