System Description

ECM controls cooling fan speed corresponding to engine speed, engine coolant temperature, refrigerant pressure, battery voltage, vehicle speed, A/C ON signal, A/C evaporator temperature, target A/C evaporator temperature and blower fan ON signal.

Cooling fan speed request signal is sent to IPDM E/R from ECM via the CAN communication line. Then, IPDM E/R sends ON/OFF pulse duty signal to cooling fan control module. Corresponding to this ON/OFF pulse duty signal, cooling fan control module gives cooling fan motor operating voltage to cooling fan motors. Cooling fan speed is controlled by duty cycle of cooling fan motor operating voltage sent from cooling fan control module.