A refrigeration appliance includes a storage compartment. An evaporator cools the storage compartment. A defrost heater is associated with the evaporator. A temperature sensor senses an evaporator temperature and generates a temperature signal based on the evaporator temperature. A controller receives the temperature signal and generates a defrost heater power control signal. A power supply receives the defrost heater power control signal and controls a power level supplied to the defrost heater based on the defrost heater power control signal. A first power level is supplied to the defrost heater during a first heating interval of a defrosting operation, and, based on an evaporator temperature rise occurring during the first heating interval, the controller adjusts the defrost heater power control signal such that an adjusted power level is supplied to the defrost heater during a second heating interval of the defrosting operation.