I have the above mentioned Samsung fridge. No self-diag codes appear on the front control panel at any time, but I noted heavy frost and ice accumulation on the evaporator coil. I followed the troubleshooting flowchart in the repair manual and the bimetal thermostat, the defrost sensor, and the heater coil all test good. When put in Manual Defrost Function, the freezer compartment defrosted correctly, but not the fridge compartment. Then I discovered that by switching the F DEF HET and R DEF HET pins on the connector on the Main Control Board DA41-00422A, that the fridge compartment would subsequently defrost and the freezer compartment did not. It appears that the problem lies on the Main Control Board, but should I troubleshoot to a component (i.e. a bad relay) or just replace the board? Also, the Main Control Board part DA41-00422A does not come up on a search on Repairclinic.com but there is a picture of my exact main control board associated with part number DA41-00413J, but I'm not sure they're compatible. Thanks for assistance.