motorhome is ascending long hills or operating in high ambient temperatures.
It is normal for the fan to “roar” when it is operating. Fan motor speed and
engine rpm are approximately the same with the switching valve at full
engagement.
The wax filled thermovalve is mounted at the top of the radiator sensing
coolant temperature. The thermovalve controls the action of the switching
valve. When the radiator is cool the hydraulic fluid is allowed to flow
through the inlet and outlet ports of the thermovalve and return to the
hydraulic reservoir. As the coolant temperature inside the radiator rises to
approximately 185° the wax inside the thermovalve begins to melt and
expand. This begins to restrict hydraulic fluid flow through the thermovalve.
The restricted hydraulic fluid pressure then begins to move the internal spool
valve of the switching valve. The process will continue until coolant temper-
ature inside the radiator reaches approximately 199°F. At this temperature
hydraulic fluid flow through the thermovalve is stopped, moving the spool
valve to full open position.
The switching valve is mounted to the fan motor. The switching valve
controls the direction of high pressure hydraulic fluid flow. High pressure
hydraulic fluid comes from the hydraulic pump to the switching valve and is
returned back to the reservoir. The thermovalve directs the fluid to the spool
valve in the switching valve. When the radiator is cool, pressurized hydraulic
fluid will bypass the fan motor and return to the fluid reservoir. As a radiator
temperature rises, the thermovalve signal is slowed or stopped to the switch-
ing valve. High pressure fluid is then directed to the fan motor, cooling the
radiator.
The fan motor is driven by hydraulic fluid pressure from the switching
valve. The fan motor works on the same mechanical principal as a hydraulic
pump, only the mechanical principal when applied to the fan motor is
reversed. Instead of creating hydraulic pressure by meshing gears together in
a close tolerance housing, the fan motor receives hydraulic pressure. The
hydraulic fluid drives the fan motor’s internal gear assembly, spinning the
fan motor and the attached fan blade.
Chassis Information
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WINDSOR
10•297
Thermovalve
Switching Valve
Fan Motor
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