Depending on the year , Model, brand. Some older timers are located on Top over Top in top or top back of refrig, some side by sides are located behind bottom front grill. . Try tapping it with a rubber screwdriver handle. It may not be advancing forward to turnbit on and off. It works much like a clock gear. You might also try putting a small flat screwdriver in the plastic round shaft to advance it til it clicks and comes on. If it does come on timer needs replacing most likely.