Grand Master RegUS_PatOff sets the table for us:

"If frost or ice is forming on freezer packages, shelving, or back wall compartment order the following kit.

Order repair kit 12002686 for both Domestic Models (115 volt) and (230 volt) International Models.

See attached Instruction Sheet for details on installing Bottom Mount Frost Kit."

TDR-0045A-B.pdf

16026499.pdf

16027094.pdf

There is also a duckbill grommet # 8201796 that can be installed over the outlet end of the drain tube.

This is the tube at the bottom of the unit, to the drain pan. It will prevent air from equalizing through the drain tube.

click on picture

Source: Amana bottom freezer ABB1921WEW0, defrost drain freezing up