Subject: Household Appliance Maintenance Issue: Blocked Fridge Drain (Frost-Free Models) 1. Abstract The blocked defrost drain is one of the most common, yet frequently misdiagnosed, issues in modern frost-free refrigerators and freezers. This paper outlines the mechanism of the defrost system, the primary causes of blockage (organic debris and ice plugs), the symptoms presented to the user, and a step-by-step remediation protocol. 2. Mechanism of Failure In frost-free refrigerators, a defrost heater periodically melts ice buildup on the evaporator coils. The resulting water flows down a channel to a drain hole (typically located at the back wall of the fresh food compartment, just above the bottom shelf). This water travels through a flexible drain tube to an evaporation pan located near the compressor, where ambient heat evaporates it.