Coolant fan override switch

[g_man1146]

Leroy,
You are correct; the fan bypass defaults to closed, thereby forcing
all of the pump output through the fan motor. Cool temperatures, air
conditioner "ON" or "Fan Override" switch "ON" all hold the bypass
valve open allowing oil to flow around the fan motor. When I was
attempting to diagnose what turned out to be a defective pump, BB
sent me a diagram and test procedure to follow. They said the LXi
shared the same system as the "LTC" commercial coach.

Rich D. '99LXi43' CT


--- In WanderlodgeForum@yahoogroups.com, "Leroy Eckert"
wrote:
>
> Rich: I have a question on the bypass valve if you know. I do not
have a drawing of the valve.
>
> As I understand the system, the fan is normally in idle(bypass)
mode until one of three things happen. The alarmstat activates high
mode based on water temperature, the fan override(manually by humans
or grandkids) activates high mode or the chassis a/c on switch
activates high mode.
> Does the fan bypass valve default to fan high mode? . That would
make sense otherwise the system would overheat with valve or
electrical failure. If so, one could conclude that the piston in the
valve is actuated by continuous power in the bypass position and the
fan override, a/c switch and alarmstat cuts power off to it and it is
spring loaded to full fan mode.
>
> If you know. Thanks. Trying to learn more here.
>
>
> Leroy Eckert
> 1990 WB-40"Smoke N Mirrors"
> Niceville,FL
>
>
>
>
>
>
> ----- Original Message -----
> From: Leroy Eckert
> To: WanderlodgeForum@yahoogroups.com
> Sent: Monday, February 19, 2007 9:35 PM
> Subject: Re: [WanderlodgeForum] Re: Coolant fan override switch
>
>
> That was to Greg, but I think we are all speaking of the same
thing, just a different component in the system with a bypass. The
fan control valve has a bypass as does the Parker filter. The
override sends a message so to speak to the valve to stop the bypass
and get into high mode. So does the chassis a/c on switch. If the
valve is bad, the fan will not spool up.
>
> Leroy Eckert
> 1990 WB-40"smoke N Mirrors"
> Niceville, FL
>
> ----- Original Message -----
> From: g_man1146
> To: WanderlodgeForum@yahoogroups.com
> Sent: Monday, February 19, 2007 9:08 PM
> Subject: [WanderlodgeForum] Re: Coolant fan override switch
>
> Gregory,
>
> On the later model Series 60's the fan bypass valve diverts
> hydraulic oil around the fan motor to allow the fan to run at a
> lower speed by sending the oil back without going through the
> fan "motor". If the bypass valve fails, you get full RPM of the
fan
> as all of the oil is directed to the fan motor. This has nothing
to
> do with a filter bypass. The bypass valve can also be tested by
> plugging the return line that goes to the bypass valve thus
forcing
> all oil through the fan motor.
>
> Rich D. '99LXi43' CT
>
> --- In WanderlodgeForum@yahoogroups.com, "Leroy Eckert"
> wrote:
> >
> > Yes.
> >
> > Leroy Eckert
> > 1990 WB-40"Smoke N Mirrors"
> > Nicevile, FL
> >
> >
> > ----- Original Message -----
> > From: Gregory OConnor
> > To: WanderlodgeForum@yahoogroups.com
> > Sent: Monday, February 19, 2007 8:02 PM
> > Subject: [WanderlodgeForum] Re: Coolant fan override switch
> >
> >
> > David, Bypass and override are two independent features. I
> believe
> > bypass is a safety feature for a clogged hydro oil filter.
> Bypass is
> > not triggered by the override dash switch
> > GregoryO'Connor
> > 94ptRomolandCa
> >
> > --- In WanderlodgeForum@yahoogroups.com, David Brady
> > wrote:
> > >
> > > 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
> > > >>
> > > >>
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > Yahoo! Groups Links
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > >
> > >
> > >
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