Troubleshoot circuit board to verify voltages. Tested thermistors for correct resistance.Checked heater circuit continuity. All above were eliminated as probable cause of failure. During day and a half of on/off troubleshooting, Evaporator fan was finally observed to “not” be running all the time compressor was on. voltage had measured ok when checked. It was a intermittent failing fan. Refrigerator running as it should. Worth the effort.