What you discribed is the defrosting cycle of the fridge, what happens is when the fridge is ready to defrost the timer shut,s the fridge off sending power to the heating element. This cycle normally last for 30 min,s. The refrigerator normal goes into a defrost cycle every 6 to 8 to 12 hours a day, depending on the timer use in the fridge. Some refrigerators have a electronic boards to do the same thing as a timer would do. So what you have just seen is a normal defrosting cycle.
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