How to Troubleshoot & Replace Ge AP3190397 / WR50X10025 Defrost Thermostat

First I replaced defrost timer but didn’t work, then I replaced the defrost thermostat and it worked, that was the problem, now I have an extra defrost timer, it only took me 30 minutes for both. 

First I replaced the defrost timer because I read this was a likely culprit. I didn't have a multimeter to test. After a week the problem re-surfaced. I researched further and found that if the Defrost Limiter Thermostat was exploded that it was probably bad. By exploded I mean that the seals on either end were uneven and burst. I replaced the thermostat and it looks like the problem is solved! 

I replaced it with a new one. Most of the time spent on the project was defrosting the evaporator with a hair dryer. 

Problem: Freezer was cold but fridge was warm. I’ve kept clogging the cool air channels from freezer to fridge. Solution: Full replacement on both the evaporator fan and the thermostat. Just a few hex head screws to remove the plastic covers then some philips head screws to remove the fan. I clip the motor wires, and repeat the process backwards for install. The thermostat was a little trickier and involved some very basic and doable wiring. I cut out the old thermostat leaving the wires that went to the power source motor and fridge cooling structure. Then just twisted and sealed the wires to their coordinating colors. That part took about 15 mins then I had to make sure all the ice blocking the channels to the fridge compartment was clear. Let the fridge run at level 5 for 4 hours and you should know if it worked. 

Used socket wrench to dismantle freezer panel assembly; Unplugged fridge & let ice melt; Cut out faulty thermostat at wires with pliers; Connect new thermostat with wire nuts & electrical tape 

Replaced the defrost thermostat and defrost heater. Its working perfect know thanks guys for all the help 

I am a novice at best. The temperature in my refrigerator was bottoming out in the 50’s but the freezer was staying in the 20’s. After some googling i figured it was a defrost issue. I emptied the freezer and took out the back panel, advanced the timer and the defrost coil didnt come on. Research said it was either the coil itself or the Defrost thermostat. I dont even own a multimeter so I didnt have the ability to properly test the coil. To play it safe i bought the thermostat and a new coil. It arrived in 2 days and i spliced the new thermostat in with crimp connectors and i plugged in the new coil, put everything back together and let the freezer cool back down. I waited for the fridge to kick into the defrost cycle and watched for the coil, When it started to faintly glow I knew it was working. The fresh food section stays between 35 and 40 freezer is holding around 22. I feel more knowledgeable and confident in my ability to make repairs in the future. 

Installed new heater and thermostat