A used fan clutch will operate at a minimum speed of 100 rpm when there is no control pressure with cold supply oil. A new fan clutch will operate at a minimum speed of 300 rpm when there is no control pressure with cold supply oil.
The fan control solenoid valve adjusts the control oil pressure to the fan clutch. The adjustments are based on the inputs from the coolant temperature sensor and inputs from the inlet manifold temperature sensor.
The fan control solenoid valve modulates the control pressure to the fan clutch. Modulating the control pressure changes the fan speed. Modulating the control pressure allows the clutch plates that are cooled in oil to slip. The slippage results in variable fan speed.
The maximum fan speed is dependent on the machine requirements. The minimum fan speed also has a lower limit in order to maintain adequate air conditioning system operation.