| 摘要 |
PROBLEM TO BE SOLVED: To control the power consumption by directly determining the quantity of frost formation in an evaporator and thereby restricting the defrosting operation to the minimum necessity. SOLUTION: A fan control means 25 drives a fan 13 to always keep the target rotational frequency by adjusting the input electric power of the fan 13 based on the rotational frequency measured by a rotational frequency measuring means 24. A defrosting heater control means 26 detects the variation of the pressure loss in an air circulation passage by the fan 13 based on the electric power inputted to the fan 13, determines the quantity of frost formation in the evaporator based on the result of the detection, and starts the defrosting operation by a defrosting heater 10 when the determined quantity of frost formation is at least a previously determined threshold for starting the defrosting.
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