Viscous Cooling Fan
| Item | Description |
|---|---|
| 1 | Top mount (2 off) |
| 2 | Electrical connector |
| 3 | Viscous Cooling Fan Control Module (VCFCM) |
| 4 | Viscous cooling fan shroud |
| 5 | Speed flap (3 off) |
| 6 | Lower mount (2 off) |
| 7 | Viscous cooling fan blade |
| 8 | Securing nut |
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 the viscous cooling fan speed for all operating conditions.
The blades of the viscous 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 viscous cooling fan to a drive pulley, which is mounted on the front of the engine and driven by the accessory belt. For additional information, Refer to: ACCESSORY DRIVE
The viscous 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 viscous cooling fan harness and the vehicle wiring.
The VCFCM is provided with:
- Two 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 viscous 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.