A defrost control system for a self-defrosting refrigerator is configured to monitor a compressor load, determine whether at least a first defrost cycle is required based on the compressor load, execute at least one defrost cycle when required; and regulate the defrost cycle to conserve energy. A controller is operatively coupled to a compressor, a defrost heater, and a refrigeration compartment temperature sensor. The controller makes defrost decisions based on temperature conditions in the refrigeration compartment in light of other events, such as refrigerator door openings, completed defrost cycles, and power up events. Defrost cycles are automatically adjusted as operating conditions change, thereby avoiding unnecessary energy consumption that would otherwise occur in a fixed defrost cycle.