That must be it then. He brought the wrong board out. Okay so that's the only control board in the frig. So the defrost timer circuit would be on there. Does my analysis sound right that it is most likely the board then? Are the evap coil thermister & thermostat checked when turning on the heater through the diagnostics? Would you say my best bet is to do the board first try?
Okay. Excellent. Exactly what I needed to know. Mucho thanks for your expert help on this!