Coolant fan override switch

[David Brady]

Hi Rich,

Thanks for the help. When I return to the bus I'll try your test.
I guess if the fan speed increases, then the problem is between
the dash switch and the "bypass valve". Alas, no wiring schematics..
I'll let you know what happens.


David B
'02 LXi, Smokey
NC

g_man1146 wrote:
> 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
>>
>>
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