After checking out three devices in the circuit off defrosting found out that defrost sensor is the one which do not have any resistant readings. ( This part actually consist of two devices: resistor and the fuse, which appeared to be burn out.) Changing a part is not a big deal. The biggest challenge is to get to this part. Unfortunately there no detailed diagram or instructions on entire internet including LG web page which is no help at all. You have to take apart literally entire freezer section if you know this part located in the freezer. Otherwise You will be taken apart entire fridge.