| 摘要 |
PURPOSE:To prevent the frequent operation of a frost-prevention mechanism by providing an auxiliary heater on the upper course side of a cooling evaporator in an air conditioner duct, and shiftingly controlling said auxiliary heater to be in an operating condition when the cooling degree on the outlet side of said evaporator is below a set value. CONSTITUTION:In an air conditioner duct 1 in which intake ports 5, 6 for selectively introducing inside air or outside air are provided on the upper course end while plural blow-out ports 14-16 are provided on the lower course end, an auxiliary heater 2, an evaporator 3, and a heater core 4 are installed in order from the upper course side toward the lower course side. Also, a cold air temp. sensor 21 as a cooling degree detecting means is provided on the air outlet side of the evaporator 3 in the air conditioner duct 1. Further, a water valve 23 as an overheat connecting/disconnecting means is provided in the advance-passage piping 26A out of hot water circulating pipings 26A, 26B for feeding engine cooling water into the auxiliary heater 2. And when a cooling degree below a set level is detected at the time of dehumidifying and heating operation, the water valve 23 is opened and the auxiliary heater 2 is operated. |
