Circuit Description
WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.
The electro-viscous clutch is controlled by the PCM. The PCM controls a solenoid that regulates a fluid pressure that controls slip of the fan clutch. Internal to the fan is a centrifugal fluid pump, solenoid, hall effect sensor, valve lever and a hydraulic fluid. There is two chambers for the fluid, these two chambers are separated by a valve lever. The first chamber is the storage chamber, which holds excess fluid. The second chamber is the working chamber. As the pressure of the fluid is increased in the working chamber the amount of slip the fan has is decreased. The position of the valve lever is controlled by an electric solenoid.