Electronic - Viscous (EVC) Fan Clutch Operation

The ECM/PCM signal controls the level of engagement of the EVC. An internal solenoid opens a spring loaded valve which allows silicone drive fluid to flow from the storage reservoir to the working area of the unit engaging the clutch. This engagement process is ultimately controlled through the ECM/PCM by the following input variables:

  • Coolant temperature
  • Engine RPM
  • Transmission oil temperature
  • A/C head pressure
  • Engine oil temperature

These variables are manufacturer specific and fan speed is dictated based on the level of cooling required. Please consult the O.E. specifications to determine which set of variables apply to your vehicle.