How to Troubleshoot & Replace Samsung AP4136157 / DA47-10160H Refrigerator Defrost Thermostat

I called a repair company to find out what's going on with the freezer the Tech inspected and said that the defroster thermostat sensor was bad, he want me to charge $500 dollars to repair it which I found it too much since the refry was 10 years old, so went to appliance Parts.com and I investigate how much was that particular sensor my surprise it cost only $27 dollars but not only that there was a video that shows how to replace it; wonderful! I order it and I replaced it myself in 20 minutes and my freezer is working fine again. Thank you Appliance parts 

Replace parts 

I followed the instruction posted on the website . 

Problems: 1. noticed water came from freezer but the fan was still running. 2. turned off power and turned on again, both fan and comp did not run. 3. checked schematic in the back, bank CN30 pin 4&5 have reading 38.8 ohms (F Def Sensor), other pins have K ohm readings. 4. checked comp starter and overload, they were fine (continuity). I ordered both defrost temperature sensor and defrost thermostat sensor but only replaced temperature sensor and it worked. The video shows the temp sensor is on the refrigerator side but it has 2 cooling coils. My refrigerator has only one coil. However, there is another temp sensor on the refrigerator side and it locates in the styrofoam.