How do you unblock a defrost drain in a refrigerator?

Unblocking a frozen or obstructed defrost drain in a residential refrigerator requires a careful manual cleaning process to restore proper water drainage. First, unplug the refrigerator from the wall outlet for safety, open the freezer compartment, and remove all food items, shelves, and the lower rear interior back panel to expose the frozen drain trough beneath the evaporator coils. Second, use a hair dryer on a warm setting or squirt warm water using a turkey baster down the drain hole to melt any solid ice plug. Third, gently push a flexible nylon pipe cleaner or a piece of stiff wire down the opening to sweep away trapped food particles or slime. You can troubleshoot drainage flow easily. You can verify that your unblocking procedure was successful when pouring a small cup of warm water into the drain trough results in water flowing unimpeded into the bottom evaporation pan without pooling.