VEHICLE-MOUNTED AIR CONDITIONER CONTROL DEVICE, AND VEHICLE

This vehicle-mounted air conditioner control device () comprises: a PTC heater (H) that is included in a high-voltage system circuit (HV) and generates heat by the power supplied from a high-voltage battery (B); and a microcomputer () that is included in the high-voltage system circuit (HV) and controls the power supply from the high-voltage battery (B) to the PTC heater (H). This vehicle-mounted air conditioner control device () further comprises: a water temperature sensor () that is included in a low-voltage system circuit (LV) and outputs a voltage signal corresponding to the temperature of hot water; and a V/f conversion unit () that is included in the low-voltage system circuit (LV) and converts the voltage signal output from the water temperature sensor () into a frequency signal. This vehicle-mounted air conditioner control device () further comprises a digital isolator () that transmits the frequency signal to the microcomputer () while maintaining electrical insulation between the V/f conversion unit () and the microcomputer ().