The insulated pipes leading into the indoor part of the AC unit was iced over.
So per instructions on online, I turned it off and let it thaw all night; changed the air filter - it was really dirty (oops, my bad) - that was likely the problem; the fan is running now (AC still off) to make sure everything melts.
My question is, is it safe to turn back on? It seems thawed. I don't want to make anything worse.