Coolant fan override switch

[Gregory OConnor]

David, A good test for fan override function is to high idle a cold
engine and throw the dash override with someone listening for air
noise. If your fan does not powerup and seems to always stay on, one
of the common causes is the a/c input( pressure switch or dash
control)

On my older 8V92DD the hydrolic pump on the engine spins the fan
motor slower at low RPM than High. The cooling fan requires a good
8% of engine power to run at 2,000 rpm. if the fan was to rotate at
a high speed at idle, that would be higher percentage of the total
horsepower produced at the reduced speed. Idle with a fast fan would
be a killer lug on the engine.

Fan override is a bad name because you are just overriding the off
end of the automatic function. Fan filterbypass is another confusing
term on the 8v92DD.
GregoryO'Connor
94ptRomolandCa

--- In WanderlodgeForum@yahoogroups.com, David Brady
wrote:
>
> Folks,
>
> On my '02 LXi, with the engine at idle, the fan seems to rotate
> at 400 rpm or so (give or take, lol), when I enable the override
> switch there doesn't seem to be any change in fan speed. Should
> there be? or are there other parameters at work hear; i.e., engine
> temp, etc. What are the common failure modes of the fan override?
>
> Thanks,
> David Brady
> '02 LXi, Smokey
> NC
>