Before attempting to unclog the refrigerator defrost drain, make sure this is the main issue. If you see these signs, the defrost drain is clogged. Find the Defrost Drain and HoleThe defrost drain is on the back of the freezer compartment, just behind the back panel. Instructions on How to Unclog Refrigerator Defrost Drain at a GlanceLocate and clear a blocked refrigerator drain hole, making use of household toolsUnplug the fridge before you begin the maintenance workLocate the drain tube at the back or in the freezer. When you understand how to unclog a refrigerator defrost drain and take preventive measures, you can avoid potential damage.