My Samsung rf23hcedtsr refrigerator section is not cooling. There was noise from the fan from ice build up, now there is none and the fan will not run. I pulled the plug and let it defrost but I am guessing the fan is shot, another is on the way (I could not get the fan to power up). I am already replacing the fan, is it likely that I need to replace the sensor & defrost thermostat too? Freezer/ice maker are fine. Hoping I am on the right track and it is not the motherboard.