Sounds like the coolant might have leaked check by unscrewing the back and see if you see a brownish line or blotch if you do your r12 is low and the tank that holds it has a small hole to fix that for temporary use some Gorilla glue and masking tape put the masking tape down first as this will act like a patch then the gorilla glue around the edges and some over the hole to make the tape bond better to the tank

Your defrost may be stuck on. Cool air is not the same as freezing air. Frost free freezers use less than freezing air passed over and through the food to warm any ice crystals and move the moisture out of the freezere.