a result the electric charge in the capacitor 7 is discharged by way of the diode 17 constant current circuit 20 and transistor 19 according to the embodiment the controller 10 controls the discharge circuit according to the signal from the cut off detecting circuit and hence discharge can be started without receiving signal from the air conditioner controller 12 in other word without receiving a cutoff signal of direct current power source from outside therefore at the time of checking or repairing by cutting off the battery 1 by detaching the connector or the like the capacitor 7 can be discharged easily if the fuse is blown meanwhile discharge can be done without requiring any particular work 0057 fig8 is a block diagram of an automobile air conditioner in embodiment 6 of the invention in fig8 same components as in fig7 are identified with same reference numerals and detailed explanation is omitted in this embodiment the cut off detecting circuit of embodiment 5 in fig7 is designed to drive the transistor 19 directly while the battery 1 is not cut off a transistor 24 is turned on by the potential voltage by the resistor 21 and resistor 22 and the collector voltage of the transistor 24 becomes about 0 v therefore the base voltage of the transistor 19 is about 0 v and the transistor 19 is in off state when.