page 3 of 3 < PREVIOUS | NEXT >

The solenoid valve is the heart of the control system, opening and closing to regulate the air flow to the fan drive.

The solenoid valve is a 3-way valve having two inlet/exhaust ports and one outlet port. Air pressure from the vehicle's air system is fed into one of the inlet ports and the outlet port is connected to the fan drive. Turning the electric current on and off causes a plunger inside the solenoid valve to move up and down. The plunger connects the valve outlet port to one of the two inlet ports:

• the normally-open port when the electric current is off.
  
• the normally-closed port when the electric current is on.
  
  

The valve has a 3/64" [1.19 mm] orifice to regulate the volume of air and ensure smooth engagement and disengagement of the fan drive.

EXAMPLE. Normal can be defined as the state of the solenoid valve if it was completely disconnected and in your hand - the solenoid would be de-energized, the normally-open port would be open to the outlet port, and the normally-closed port would be closed to the outlet port.

The valve outlet port is always connected to the fan drive. Depending on the vehicle's electrical control circuits, the air supply may be connected to either the normally-open or the normally-closed port. The port not connected to the air supply will exhaust air from the fan drive when it disengages.

Various adapters and fittings are available to permit the solenoid valve to be plumbed either normally-open or normally-closed (i.e., the air supply may be connected to either inlet port). These fittings also permit the solenoid valve to be installed with or without an air filter.

Mount the solenoid valve in a remote location away from the engine to minimize the valve's exposure to excessive heat, vibration, and contaminants. A solenoid valve mounted off of the engine will prolong the life of the solenoid and ensure proper fan drive operation.

page 3 of 3 < PREVIOUS | NEXT >