Engine Cooling Fans
Depending on market and model specification, vehicles have either a viscous cooling fan, or a viscous cooling fan and an electric cooling fan, to help regulate the coolant temperature.
Viscous Cooling Fan
| ITEM | DESCRIPTION |
|---|---|
| 1 | Shroud |
| 2 | Mounting lugs |
| 3 | Electrical connector |
| 4 | Electro viscous drive unit |
| 5 | Speed flap |
| 6 | Mounting lugs |
| 7 | Securing nut |
| 8 | Speed flaps |
The viscous cooling fan functions as a normal viscous fan, but with electronic control over the level of engagement of the viscous clutch. The Powertrain Control Module (PCM) controls the level of engagement to optimize fan speed for all operating conditions.
The blades of the cooling fan are located in a shroud attached to the rear of the radiator. The shroud incorporates speed flaps, which pivot open to allow engine compartment cooling at speed. A securing nut attaches the cooling fan to a drive pulley, which is mounted on the front of the engine and driven by the accessory drive system.
For additional information, refer to: ACCESSORY DRIVE .
The viscous engine cooling fan is operated by the Viscous Cooling Fan Control Module (VCFCM), integrated into the drive unit, which is controlled by the PCM. An electrical connector in the top right corner of the shroud provides the interface between the cooling fan harness and the vehicle wiring.
The VCFCM is provided with:
- Two battery power supplies from the PCM relay in the Engine Junction Box (EJB)
- A Pulse Width Modulation (PWM) signal from the PCM
- A ground.
A Hall effect sensor in the VCFCM provides a fan speed signal for the PCM.
To control the cooling fan, the PCM varies the duty cycle of the PWM signal. The VCFCM translates the duty cycle into a fan target speed and sets the level of engagement of the viscous clutch accordingly.
Electric Cooling Fan - If Equipped
| ITEM | DESCRIPTION |
|---|---|
| 1 | Shroud |
| 2 | Mounting lugs |
| 3 | Speed flaps |
| 4 | Electric cooling fan |
| 5 | Speed flaps |
| 6 | Mounting lugs |
| 7 | Speed flaps |
| 8 | Electrical connector |
| 9 | Speed flaps |
The electric engine cooling fan is a variable speed fan installed in a shroud attached to the front of the radiator. The shroud incorporates speed flaps, which pivot open to allow engine compartment cooling at speed.
The cooling fan is operated by the engine cooling fan control module, integrated into the electric motor, which is controlled by the PCM. An electrical connector at the right side of the fan shroud provides the interface between the cooling fan harnesses and the vehicle wiring.
The fan control module is provided with:
- A battery power supply from EJB
- An ignition signal from the PCM relay in the EJB
- A PWM signal from the PCM
- A ground.
To control the cooling fan, the PCM varies the duty cycle of the PWM signal. The engine cooling fan control module translates the duty cycle into a fan target speed and sets the output current to the fan motor accordingly.