| 摘要 |
<p>PURPOSE:To enable a uniform increasing of a temperature of a cooling unit to be carried out and a defrosting operation to be performed within a short period of time by a method wherein a changing-over switch for making a selective energization of heaters arranged at two locations of an air flow outlet and a central part of the cooling unit when a defrosting operation is carried out. CONSTITUTION:Defrosting heaters 18A and 18B are arranged near an air flow inlet port of a cooling unit 11, and a defrosting heater 18C is arranged at a central part of the cooling unit 11. A changing-over switch 20 installed in the midway part between set positions of the defrosting heaters 18A and 18B and the defrosting heater 18C may close an energization circuit for the defrosting heater 18B at first. As the set locations show a predetermined temperature, a circuit for the defrosting heater 18B is opened and a circuit for the defrosting heater 18C is closed. With this arrangement, when a defrosting operation is carried out, at first a defrosting at the lower part of the cooling unit is carried out and after that, a defrosting at the upper part is carried out, so that the defrosting can be entirely performed within a short period of time.</p> |
