The defrost temperature sensor appeared to be intermittent. Sometimes the resistance was correct, other times it was open. Followed the very good instructive video and noticed the factory installed sensor was mounted incorrectly. The cardboard protective side was mounted against the evaporator coil. The video clearly showed and the gentlemen stated the clear side should be placed on the coil. That make sense. My fridge is slightly different then that shown in the video. Mine is a compact unit sans ice maker. There were 5 screws to remove the back panel, very easy to take it off and put it back.
Was an easy fix.