What to do? Avanti RA3103SST compressor does not stop?

This 2-door compact (under-counter) refrigerator/freezer Avanti RA3103SST stands the same way, same distance from walls, properly plugged in as before. After complete manual defrosting of ice in both cabinet sections noticed the reason for the ice build-up: compressor never stops, so the automatic defrosting cycle cannot kick in. How can that be fixed? Is there a way to check where the evaporator tray is, whether its melted ice conducting channel is clogged and then to learn how to clean it?