You're probably going to find the evaporator coil in the freezer choked in with frost, in which case, the problem is almost always the infamous Jazz Control Board.

There's a tech sheet in the toe grill that tells how to put the board in diagnostic mode for various tests. But the most common failures with this board are 1) failing to initiate defrost and 2) keeping compressor running during defrost. Both result in a frosted up evaporator coil.

Put the unit into forced defrost. If the defrost heater fires up, that means the defrost heater and limiter are good. Then go ahead and replace the Jazz Board.

Here's my video showing how to do the diagnostic dance:

Source: Kenmore/Amana Bottom Mount 596.65939401