DEFROSTING CONTROL UNIT OF AIR CONDITIONER

PURPOSE:To make it possible to detect the frosting of an outdoor side heat exchanger on the indoor side by detecting the temperatures at the inlet portion and the control portion of a pipeline of an indoor side heat exchanger. CONSTITUTION:Pipeline temperature detecting elements 6 and 6' are mounted on the coolant inlet side and the central portion of an indoor side heat exchanger 3, respectively. When an outdoor heat exchanger 5 is not frosted yet the absorbed coolant temperature Ts of a compressor 1, an inlet pipeline temperature t1 and a pipeline temperature t2 at the central portion are all high. In accordance with the advance of frosting, these temperatures are gradually lowered, and when they reach a frosting condition, the inlet pipeline temperature is extremely lowered, and simultaneously the pipeline temperature t2 is lowered, thus eliminating the temperature difference. When the difference in the temperature between the inlet pipeline temperature t1 and the central portion pipeline temperature t2 becomes less than the set pipeline temperature (t), the defrosting operation is started.