System Description
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
The cooling fan system of this vehicle cools both engine cooling main radiator and charge air cooler (CAC) cooling sub radiator with the same cooling fan. There are two cooling fan speed requests as follows:
- Cooling fan speed request for cooling the engine.
- Cooling fan request for cooling the charge air cooler.
ECM compares these requested speeds and transmits faster one to IPDM E/R as a cooling fan control signal.
Cooling fan control signal is sent to IPDM E/R from ECM by 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.
Cooling Fan Speed Request for Cooling the Engine
Cooling fan speed for cooling the engine is judged based on vehicle speed, engine coolant temperature, air conditioner ON signal, refrigerant pressure, target A/C evaporator temperature, and A/C evaporator temperature.
Cooling Fan Speed Request for Cooling the Charge Air Cooler
To judge a cooling fan speed for cooling the charge air cooler, ECM monitors an estimated ambient temperature and a CAC coolant temperature calculated based on a CAC coolant temperature sensor signal.