The control circuit diagram found open air A / C, the right "220V AC Cooling Fan" motor two lines measured, Fire Wire is a voltage, and a ground wire has been in the off state. And the ground wire from the 2nd fan relay, air pressure switch, air conditioning amplifier, the engine ECU and the fan resistor switch between each other to complete. When the high side pressure exceeds 1.5MPa, the ground wire can be turned on, "220V AC Cooling Fan" motor to work properly, the air conditioning pressure switch and the 2nd fan relay in question is unlikely. From the line chart, the air conditioning amplifier only receive radiator fan motor is switched from low-speed signal, the engine ECU and air pressure switches are low-speed switching speed fan motor control, this time "220V AC Cooling Fan" low speed are not, so most likely the fan resistor.