This is the best way to unclog a sub-zero drain tube.
This is extremely common on newer Sub Zero models made since the year 2008 that are in the side-by-side configuration￼.
Bi-48s bi-42s bi-36s Are the common models where this will apply but the concept is the same just about all refrigerators that use a condensation line into a pan￼.
Basically, You need to locate the drain hole and use a pipe cleaner or small diameter piece of metal to unclog the drain. A coat hanger works great. Watch the video to learn how we perform this service and see if you can do it yourself.