The system consists of an engine-driven pump with an integral solenoid (Figure 50) on the pump that is triggered by the powertrain control module (PCM). Fan speed is controlled by adjusting current to the solenoid, which then changes the fluid flow to the hydraulic motor. More current means the solenoid opens up, allowing higher pressure to increase the fan speed. The fan always turns due to solenoid current leakage, even in cold engine cases. The motor is driven by the pump. It contains a shaft on which the fan mounts. The motor also contains quick connect fittings for the high pressure lines. The cooler is similar to the power steering cooler (same purpose and function, to keep the fluid cool).
