How to Troubleshoot & Replace Lg AP4438477 / 6615JB2005H Defrost Sensor Assembly

I have had the unfortunate problem of fixing this previously, so knew what to order. I ordered the defrost sensor and heater... and replaced both. Honestly, all I needed was the sensor I did and ohm test and got 0 on it... meaning it was bad, but just in case I replaced the heater. The fridge works great now, but I would suggest if this is your first time with this issue, remove the panel, unplug both sensors from the fridge, and do and ohm test while they are still in the fridge... and then replace the defective component... which is most likely just the sensor. 

I manually defrosted the evaporator coils, then replaced the defrost sensor. After reassembly, the fridge now works properly and no more trouble keeping codes. 

Flawless… thanks to the outstanding video provided with the part, the repair was super easy when the unforeseen benefit was cleaning out the entire refrigerator/freezer. Amazing the things you didn't know existed! If anyone has do it yourself genetics, this is the place to shop. Thanks guys 

Could not have done it without this app, it told me everything to do. 

I went online to Appliance Parts Pros and ended up chatting with a representative who guided me in the right direction. It was the defrost element, and I also took his advice and changed the sensor. 

Replaced ice maker fan - Did not fix the IR code. Replaced defrost sensor, Main Pcb assembly and capacitor because I would be in that area changing the Pcb. Everything works like new. The Main Pcb most likely fixed all problems but the defrost sensor and capacitor were cheap and I didn't want to take anything to chance. So far all is working again - $150 for repair parts vs $2500 for new refrigerator. ?? The Pcb and capacitor took 15 min to replace, easy access on back of refrigerator. The defrost sensor took about an hour because the freezer drawer and slides rails have to come off to get the back wall of freezer out. 

I'v e taken the freezer apart before for a plugged drain hole. Was hoping this was the same thing but it was not. Did some research for possible causes and came up with 2. 1- door not sealing and defrost cycle not working. The door seal could be it but I had not noticed the seal until after the ice started to b build up. So I went with option #2, the defrost cycle. Being a DIY type of guy (or wantabe) I checked out the web and the videos and ordered this parts. I took pictures with my phone for the wire routing and zip tie locations, etc. Everything went just as planned except for 1 thing. The replacement sensor did not come with AL tape around it. I was able to peal enough (?) from the old one to cover the new one. Then got everything in place and put back together. The videos where a huge help. Don't forget the tin snips for the heating element holder on the right lower side. 

I replaced both the Temp Sensor and the Defrost Sensor Asy. Turned out that the Defrost Sensor was bad. That caused the inlet for the DRAIN HOSE to freeze up, That caused water to build up under Evaporator and freeze, That caused water to build up and freeze under the freezer tray. The discovery happened while changing the Defrost Sensor Asy. 

We replaced the Main PCB Assembly. 

We followed the video created by Appliance Parts Pros and replaced the defrost sensor. We replaced the gasket just for good measure. The video was so helpful and the refrigerator is humming as normal again! The only difference between our refrigerator and the one in the video was the connecting rod for the lower drawer. We had to push the sliding arms all the way to the back to get the connecting rod back in.