Nikki P
The ice should not be melting if your freezer is set properly. It may be evaporating.
Frost Free units remove moisture from the air preventing ice from building up. If it is removing moisture it is slowly removing moisture from items in the freezer. This is why you may get "freezer burn" on items that have been in the freezer for a while. Even more if they are not wrapped properly or completely exposed as ice might be.