The dreaded FF error seems to be common to LG refrigerators.
Here's my situation: Got the FF error. Took out the back panel of the freezer and there were some sizeable chunks of ice. Got things clean and dry and put it back together -- no error, fridge ran great. Three days later (this morning) FF error again. Took the panel out, powered it up, and the fan was spinning, no FF error. Put it back together, running fine.
Now I know this unit isn't done screwing with me. And I've seen advice in other posts to this forum to just replace both the evap fan and the muthaboard and don't screw around. But that's $175-$200 and I'm certainly not convinced that there is a problem with board; and I've seen the fan running just fine. And that offends my DIY sensibilities.
I'm thinking the problem may be that the motor shaft is sticking -- maybe a little moisture in the bearing, just enough to freeze it up and give me the FF code. Then take it apart, problem goes away -- until next time. So I'm wondering if there's any low-temp, moisture-displacing, lubricant that someone might recommend for me to try to work into the bearings/seals for the motor. (Haven't taken the motor off of the back panel to see whether it is even practical to try this. Figured I'd post here, first.)