Viscous Cooling Fan
| ITEM | DESCRIPTION |
|---|---|
| 1 | Upper shroud |
| 2 | Electrical connector |
| 3 | Electric cooling fan blade |
| 4 | Lower shroud |
| 5 | Nut |
| 6 | Air flow flap (quantity 7) |
The viscous cooling fan is installed behind the radiator. The viscous cooling fan functions as a normal 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.
A securing nut attaches the cooling fan to a drive pulley. The drive pulley is mounted on the front of the engine and driven by the accessory drive system.
For additional information, refer to: ACCESSORY DRIVE
The viscous cooling fan has the following hardwired connections:
- Power supply from the PCM relay in the Engine Junction Box (EJB) (quantity 2)
- Pulse Width Modulation (PWM) signal from the PCM
- Fan speed signal to the PCM
- Ground.
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.
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.