How to Troubleshoot & Replace Samsung AP4135568 / DA32-10105S Refrigerator Temperature Sensor

Changed all sensors in the freezer and the fridge along with a new board. My guess in what the real issue was, ended up being related to the fridges "Thermal Fuse", since I found melted insulated tape on the defrosting coil. I first changed out the board and the sensors and it still failed to function. I then changed out the Thermal Fuses and the Start Relay along with the ice makers sensor. Basically a trial and error project, but finalizing that it was the Thermal Fuses actually fixing the problem. 

Tested the refrigerator evaporator fan and it would not run. Ordered evaporator motor and fan blade just in case. I went ahead and replaced sensor just as a preventive measure. Did not take long. forgot to order fan clip, but was able to salvage old one. Works Great. 

Replace Temp sensor, thermo fuse 

Because of the ice build up I concluded that the heater coil was not cycling on, therefore I started with the sensor that monitored the cooling coil. It has been two weeks the fridge is nice and cold without ice building up on the back wall. I believe starting the sensor after check the heater coil and fuse link was a good move. In the end $13.00 was not a lot to spend in repair the problem. I'm glad I was about to get this part from ApplianePartsPros.com in today with help save all that I had in my fridge. Thanks guys. Hey it took only about half hour to do. 

I changed the temperature sensor which runs into the blue disk on back wall of the fridge section as well as the temporature sensor on the defrost unit behind the back wall of the unit. 

Found repair manual and used self-check to confirm that the thermal fuse and temperature sensor were at fault. Thankfully I bought 2 thermal fuses. All the videos show the condenser coils in the refrigerator (we have a bottom freezer). So emptied it out and took it apart to the condenser. It had ice on it which I was expecting and some black burn marks (making me think that the fuse maybe burned up). Replaced fuse and sensor. Used opportunity to thoroughly clean all the shelves which were needing it. 30 minutes later, freezer was at 25 degrees again. Turns out there is a condenser in the freezer section too (makes sense now). So emptied and apart came the bottom freezer. That condenser was a solid block of ice. Had to use hair dryer to thaw it before I could work on it. Replaced fuse and sensor and working perfectly now, running at -2 degrees. No harm, no foul, but ended up taking 4 hours since I had to do both sections and its my own fault for not thinking there would be a condenser for each the freezer and the fridge. On the bright side, gained the experience and now can add fridge repair to my DIY resume! 

I looked up the parts that seemed to be related to freezer temperature, bought them, received them, and installed them. Freezer works great! Thank for all the availble info, I'm no appliance professional.