Electric Cooling Fan
| ITEM | DESCRIPTION |
|---|---|
| 1 | Auxiliary electric cooling fan motor |
| 2 | Auxiliary electric cooling fan blade |
| 3 | Top mount (2 off) |
| 4 | Speed flap (4 off) |
| 5 | Electrical connector - Auxiliary electric cooling fan |
| 6 | Electrical connector - Main electric cooling fan |
| 7 | Main electric cooling fan blade |
| 8 | Main electric cooling fan motor |
| 9 | Lower mount (2 off) |
| 10 | Electric cooling fan shroud |
Two electric, variable speed cooling fans are installed in a shroud attached to the rear of the radiator. Each electric cooling fan is operated by the related engine cooling fan control module, which is integrated into the electric cooling fan motor. The Powertrain Control Module (PCM) controls the engine cooling fan control modules via a Pulse Width Modulation (PWM) signal. Electrical connectors at the right side of the shroud provide the interface between the electric cooling fan harnesses and the vehicle wiring.
Each engine cooling fan control module is provided with:
- A power supply from the Engine Junction Box (EJB).
- An ignition signal from the PCM relay in the EJB.
- A PWM signal from the PCM.
- A ground.
The system is protected against abnormal internal temperature by measuring its internal temperature at 2 points with temperature sensors.
- Sensor 1: This sensor is used to calculate the temperature of active components near the micro controller. The electric cooling fan will stop immediately if the internal temperature reaches 135°C (275°F). At motor stop, after a delay of 120 seconds the diagnostic feedback will be sent. Normal operation will resume once the temperature is less than 120°C (248°F).
- Sensor 2: This sensor is used to measure the temperature of the power stage of the Printed Circuit Board (PCB) to reduce the power if the temperature is too high and to stop the motor in case of an over temperature condition.
The electric cooling fan will derate if the powerstage internal temperature reaches 135°C (275°F) and stop motor function at 145°C (293°F). At motor stop, after a delay of 120 seconds the diagnostic feedback will be sent. Normal fan operation will resume once the powerstage temperature falls to 135°C (275°F).
To control each electric cooling fan, the PCM varies the duty cycle of the PWM signal. The cooling fan control module translates the duty cycle into an electric cooling fan target speed and sets the output current to the electric cooling fan motor accordingly.