Side by side runs intermittent.

Refrigerator runs and cools great sometime. It seems that when it shuts off normally it will not start again. I can make it start up again by a single tap on the temp control knob housing.

I cleaned the condenser coils and made sure the fan is running when rest of unit is, made sure the evaporator fan is running. Made sure damper opens and closes and air flows through.

I thought it was the defrost timer so I replaced the defrost control board with harness. When it's running it works flawless. Please help!