Let the refrigerator defrost over night, plus used a hair dryer to speed up the process. Removed back panel on inside (twin cooling on it ) along with Styrofoam insulation, careful here must unplug wires .Replace temp sensor between panel and insulation. Next replace sensor at the back of the fridge located on evaporator coil tube, next was to replace drain tube defroster ( must remove factory one by drilling out rivet) careful not to damage evap coil replace with new one which looks a little different. It is wider and longer to retain more heat to keep drain tube from freezing up.