First I had to determine why the evaporator coil was freezing up . There are four parts that if any of the four are defective will cause your evaporator coil to freeze up. #1 evaporator fan #2 defrost heater #3 defrost timer and #4 defrost thermostat. With an ohm meter I checked my defrost heater, which checked good . Next I checked my evaporator fan , a simple way to check is to plug in your refrigerator , open the freezer door and listen to hear the fan blowing. My fan was working ok. That meant that either the defrost timer or the defrost thermostat were my problem. Since there is no simple way to check them I replaced both . When your evaporator coil freezes up food in your freezer start thawing, and items in your fridge warming up.