To avoid $200.00 repair cost, I tried to do it my self. Most refrigerators having this problem, needs to replace defrost timer. But this GE Profile Refrigerator does not use defrost timer, so this problem must be caused by one of the 3 elements, thermostat or sensor or heating coil. I am lucky to purchase the thermostat from Appliance Parts Pro for less than $20.00 including shipping fee.After 3 days delay due to shipping time, my refrigerator is working fine now.
Thank you Appliance Parts Pros.