How I Repaired an LG Fridge
Back in March, my wife noticed one evening that the ice cream in the freezer was easier to scoop, not as cold. The following morning, the fridge had a pool of water under it. Placing a thermometer inside, the temperature was reading nearly 50 Fahrenheit.
The fridge, an LG LMXS27626S, is a 2017 model. In 2020, the linear compressor appears to have been replaced by the prior owner and received a software update.
I rented an A/C gauge set from O'Reilly Auto Parts. The refrigeration system has two ports -- a high pressure port where refrigerant is compressed, and a low pressure port where refrigerant returns to the compressor. The low pressure port should normally read around 0 psi. Mine was reading deeply negative, -15 psi, meaning the system was low on refrigerant, meaning there was a leak.
I found a video on YouTube of a 2014 LG fridge that developed a leak -- condensation from the evaporator dripped onto steel tubing used to carry refrigerant and corroded it, causing a hole to develop that leaked coolant. I wondered if my fridge could have the same issue.
I cut away the sheet metal backing and scraped out the cyclopentane insulation. And sure enough, found steel tubing beneath the evaporator, surrounded by wet, or rather soaked, cyclopentane. The tubing has visible corrosion, and the insulation had visible rust.
Now, how to plug the leak? I cleaned and dried the area as best as I could. Then, I evacuated (i.e. applied vacuum) using a rented A/C vacuum pump from the auto parts store, and applied two-part JB weld epoxy around the tubing. The idea is that the hole was likely very small -- the vacuum would suck the viscous epoxy into the pin hole a bit, enough to get it to wedge itself in the pinhole, but not enough to cause any blockage of the tube. I applied it in a ring for structural integrity, so that it didn't get pushed out by the up to 120 psi of pressure that would be applied when the system was operational -- this was the high pressure side. I let that set for several hours, then refilled the system with 5.6 ounces of R-134a refrigerant, as called for on the fridge door label -- I used a small scale to measure out 5.6 ounces, and ensured the negative pressure port read ~0 psi once filled.
It has been over 3 months since the fix, and the fridge has been running cold again.
I'm not sure why LG chose steel tubing over copper. My guess is cost -- copper tubing is more expensive, but it doesn't rust the way steel does. I'm also not sure why LG didn't route water from the evaoprator away from this tubing, or why this design flaw was not fixed between 2014 and 2017 (and perhaps even exists today -- I have not taken apart any other fridges). It does make me distrust LG engineering -- when replacing my washer/dryer, I went with a different brand.