A method for controlling a refrigerator includes providing an initial input value to a heater configured to supply heat to an evaporator, performing a continuous operation of the heater based on the initial input value to increase a temperature of the evaporator to a predetermined temperature, determining a period of time taken to increase the temperature of the evaporator to the predetermined temperature, determining whether the period of time is within a reference period of time, operating the heater based on a first input value that is equal to the initial input value based on a determination that the period of time is outside of the reference period of time, and operating the heater based on a second input value that is less than the initial input value based on a determination that the period of time is within the reference period of time.