LG refrigerator LSC26905TT not freezing and frost build up on back wall

Refrigerator & Freezer Repair
1

Please make sure to click on General above and select the correct appliance type first.

Brand: LG
Model Number: LSC26905TT
Main Symptom: Freezer/Fridge not freezing/cooling
What happens & when: Frost builds up on back wall of freezer

Error Code (if any): Top four bars of freezer temp display are the only lights showing on the control display
Parts or tests already tried: Replaced Main Pcb Power Control Board
Photos / video link:

2

This could be a number of things in the actual defrost system, including the heater, the fuse, and temps sensors. The problem is that you have a user interface AP4858246 that needs to be replaced from the description, and that UI has been discontinued by the manufacturer and is no longer available for purchase. That board holds quite a bit of the operating logic and could be causing your defrost/cooling issues.

https://www.appliancepartspros.com/lg-power-control-board-6871jb1391b-ap4858246.html

3

Thank you for that response. When I unplug and replug the refrigerator the display works fine. I can adjust temp settings, choose between water/ice and turn light on/off. After several hours the lights on the display go out except for top for on the freezer temp selector. I found a post from a different forum that said the four bars on the freezer temp selector was a ‘fault code’ and probably related to a defrost sensor assembly and gave this part# 6615JB2005S. But that part is not compatible with my model refrigerator. So I’m wondering is that’s accurate about the ‘fault code’ and what part would you recommend for my make/model?

4

Ah, that makes sense. That does show as a defrost circuit failure fault code.

Either the defrost sensor assembly AP4513414 or the defrost heater AP6302236.

The sensor in question has 2 orange wires going to it. If you access the connector behind the evap cover for it, it’ll have blue, brown, and 2 orange wires. Disconnect that, take that assembly out, place the sensor with the 2 orange wires in ice water for about 5-10 minutes and take a resistance reading. Should be about 7.8k ohms at 32 degrees F.

https://www.appliancepartspros.com/lg-controller-assembly-acm55859001-ap4513414.html

https://www.appliancepartspros.com/lg-heater-sheath-5300jb1102h-ap6302236.html