I have an LG model LRBN20512WW refrigerator with bottom freezer, maybe 10-12 years old, give or take, that has developed two issues this past year. First, it started to have ice build-up on the floor of the freezer, clogged drain hole which I've cleared several times with hot water etc. There's little to no unusual frost on things in the freezer. I'm thinking from web reading that this could be the defrost thermister needing replacement, but open to ideas.
Several months after this appeared, the fridge developed a low vibrating hum (different from the buzzing hum of a compressor) when the fans are on. I took out the evaporator fan (inside the back of the freezer, where I think the noise is coming from) and it looks okay visually, spins fine without any noise.. I think there's nothing wrong with the condenser fan either, though I need to pull this out and investigate it again more closely (read somewhere recently that both of those fans go on and off in sync), to rule out an obvious issue there.
Questions I'm pondering: Could these issues be related? Could the noise be a bad fan motor? A loose fan blade assembly? What else am I not thinking of?
Any ideas or suggestions would be greatly appreciated!