Answer to: Fridge isn't cooling and has ice build-up. How do I fix it?I have a GE side by side model gss23wstass about 8 years old. The freezer temp started going up. I took off the back panel inside the freezer and noticed the defrost heater would go on but only melt the bottom part of the evaporator coils. I replaced the thermistor that clips on to the top tubing of the evaporator. I got it on ebay for about $7. It did the trick. It has been working great for the last couple weeks. Completely defrosts the evaporator. So if you have a partially melted evap. coil it could be due to the thermistor.