HMMWV FAN MODULE

[Inspector 1]

I never really paid attention to the operation of the fan because my vehicle runs at a consistent 200 degrees whether the outside temperature is 100 degrees or 40 degrees. Today I observed the fan spinning at idle. When I increased the RPM the fan did not increase in speed. I let the engine get to normal operating temperature. Increased RPM with no increase in fan speed . I disconnected the Time Delay Fan Module and watched the fan speed increase in speed when I increased the RPM's. Is this the way the module is intended to work? When module is plugged in at what point does the fan speed, increase if at all? I currently have the Fan Module plugged back in.

 

[Coug]

I never really paid attention to the operation of the fan because my vehicle runs at a consistent 200 degrees whether the outside temperature is 100 degrees or 40 degrees. Today I observed the fan spinning at idle. When I increased the RPM the fan did not increase in speed. I let the engine get to normal operating temperature. Increased RPM with no increase in fan speed . I disconnected the Time Delay Fan Module and watched the fan speed increase in speed when I increased the RPM's. Is this the way the module is intended to work? When module is plugged in at what point does the fan speed, increase if at all? I currently have the Fan Module plugged back in.

When it's not too hot, the fan just freewheels. Or somewhat close to freewheeling, there is still a little bit of friction in the hub through bearings and such that the fan spins a bit, but only a little bit as the air resistance slows it down.
This would be unaffected by engine speed.

From your description it sounds like everything is functioning how it was designed to.

The fan module has 2 settings, on and off. Either it's spinning under power or it is freewheeling.
It only locks up when you hit in the 220-230 degree range (though the gauges are notoriously unreliable, so as long as it comes on when the engine is really hot and turns off after the temp drops a little bit, you're good to go)

 

[Inspector 1]

When it's not too hot, the fan just freewheels. Or somewhat close to freewheeling, there is still a little bit of friction in the hub through bearings and such that the fan spins a bit, but only a little bit as the air resistance slows it down.
This would be unaffected by engine speed.

From your description it sounds like everything is functioning how it was designed to.

The fan module has 2 settings, on and off. Either it's spinning under power or it is freewheeling.
It only locks up when you hit in the 220-230 degree range (though the gauges are notoriously unreliable, so as long as it comes on when the engine is really hot and turns off after the temp drops a little bit, you're good to go)

That's great to know. Thank you for your knowledge.