My freezer evaporator coils are frozen and the FF section is warm. What is the problem?

The Fresh Food Section of my Whirlpool Fridge (model GS6SHEXNS00) is warm and not getting any cold air through the distribution vent from the freezer section. I noticed that the freezer coils were frozen. The condenser fan is working, the evaporator fan is working, the condenser coils have been vacuumed. I defrosted the evaporator coils manually with a hair blow dryer. At this point, I'm looking at diagnosing 2 suspect parts (the defrost heater, the defrost thermostat) with an Ohmmeter. Am I missing anything?