GE fridge issue

Hi, guys.
I worked on domestic fridges long time ago and have limited experience to work on fridges with electronic controls. Recently, I checked one side by side GE fridge Mod. GSR23YBTASS. Owners complained that several times ice cream melted and was refrozen again. I think it can happened when fridge over defrosted. Checked defrost termination thermostat L140-30. It works ok. However, my concern that it open at 140F or 60C and I think this is too high. Is this operating thermostat or safety? Additionally, I found that white electronic probe connected to the suction line. What is it?