Coolant fan override switch

[g_man1146]

Hi David,

AS others have stated, a fan over-ride failure should fault to high
speed. If you are not getting high fan speed with the air conditioner
on or with the switch set to "over-ride" locate (assuming Detroit S60)
a connector plug at the rear of the engine compartment (closest to rear
bumper) on the fan side. You should see a hydraulic hose from the fan
motor to this block (bypass valve) and wires coming from it. If you
disconnect the connector plug on these wires, the fan should come up to
full RPM. (ROAR) If it increases but not fully, the problem may lie
with the hydraulic pump which is attached to the PTO on the curb side
of the Allison or with the hydraulic bypass valve. BB makes changes all
the time and my coach (3 years older) may not be set up the same. If
you are not overheating on long hills everything may be normal. I
experienced an overheating situation only in extreme situations and
determined the problem to be a faulty hydraulic pump supplied as part
of the PTO recall from BB. The pump did not have sufficient capacity to
run the fan at full speed. They supplied a new pump and labor to
install. The fan motor is actually rated at about 40 HP at full
capacity. No wonder it is designed to cut back when not needed!

Rich D. '99LXi43' CT

--- 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
>