Our Freezer kept thawing out and we suspect that this was due to the drain in the back having been clogged/blocked which resulted in the coil to freeze. Inside the unit is a large panel, behind it is a coil. We dont believe this should NOT be frozen!! NOTE: the freezer is "frostless"
Our drain (inside) at the bottom middle was clogged with things!
we removed this and began putting warm water directly on the coil.

We are still waiting to see if the freezer gets back to the low temperatures! (it above freezing because liquids inside thawed).

Good luck!!

Anton C.