Clicking noise drives the dog crazy

Refrigerator is going on 15 years and still both refrigerator and freezer are working. For the last 3 months, when the compressor comes on, there is a slight clicking noise in the lower left section of the refrigerator. This clicking noise is like a bad electrical connection sound. The sound drives the dog crazy as she tries to find a way out. Even turning away from treats, our Chihuahua runs to the closet and hides.
Does she know something we don’t know?