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+--- Thread: Coolant fan override switch (/showthread.php?tid=4363)
Pages: 1 2
Coolant fan override switch - David Brady - 02-18-2007 16:36
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
Coolant fan override switch - Gregory OConnor - 02-18-2007 17:14
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
>
Coolant fan override switch - Richard Hayden - 02-18-2007 21:39
David,
I just wondered the same thing and at idle it definitely did make a difference
when I switched on the fan override. I could hear the difference also.
Dick Hayden - '87 PT 38 - Lake Stevens, WA
----- Original Message -----
From: David Brady
To: WanderlodgeForum@yahoogroups.com
Sent: Sunday, February 18, 2007 8:36 PM
Subject: [WanderlodgeForum] Coolant fan override switch
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
[Non-text portions of this message have been removed]
Coolant fan override switch - Leroy Eckert - 02-19-2007 03:17
This is exactly how my system works. I would think yours is similar.
1.With the fan override off and chassis a/c off the fan will spool between
approx 400x600 RPM. This continues until the temperature reaches 195 degrees,
(190 degrees now in my coach) then an alarmstat turns the fan to high speed
approx. 1800 RPM. The alarmstat operates in an 8 to10 degree range, therefore
cycling the fan from idle to high mode over and over again, hence the cycling
you may see on the engine water temperature gauge. ( you will not see the
cycling with the chassis a/c on.) you may not see cycling in this configuration
in hot temperatures or while climbing hills.
2. Fan override off, and chassis a/c on: When the chassis a/c switch is turned
on( either pilot or co-pilot) the fan goes into high mode, stays in high mode
until the a/c switch is turned off. This takes the fan override and the
alarmstat out of the system, and provides additional continuous cooling air for
the condenser. My condenser covers the top half of the radiator. Earlier
models a/c condenser are on the roof, cooled by electric fans.
3. Fan override on, chassis a/c off. Operates the same as item 2. except the
fan override switch has now taken the Alarmstat out of the system. Using this
switch in winter in my coach holds the engine water temperature at engine
thermostat value approx. 170-175. I expect to see continuous 190 or less in
summer in this configuration.
4. When my alarmstat failed/or became intermittent I experienced creeping heat.
I'm told that alarmstat failure is suppose to default to fan high mode. I have
not verified that.
4. So you see, Bluebirds engineers forced our coaches to run on the high side of
the DD specified range ( 170-210max, alarmed at 215 degrees: Ref: 13.12 DD
Service Manual Pg. 13-48) by specifying the 195 degree alarmstat. Presumably,
the thinking is that high fan RPM robs power so the higher you run the
temperature the less fan activity. Unfortunately, that simply isn't the case
because once the 195 degree temperature is attained the fan cycles continuously
anyway. It does the same thing in my bus using a 190 degree alarmstat ,
however, the benefit of the lower water temperature is lower engine oil, tranny
and retarder temperatures.
When it gets hot, I intend to use my VMSpc to evaluate the temperature
differences resulting from my alarmstat value change from 195 degree to 190
degree. I fully expect to see a 6-8 percent reduction in drivetrain component
temperatures.
The foregoing post has been documented with temperature values, estimated
outside air temps and road conditions while driving my 1990 WB-40 over the past
5 months.
Leroy Eckert
1990 WB-40
"Smoke N Mirrors"
----- Original Message -----
From: David Brady
To: WanderlodgeForum@yahoogroups.com
Sent: Sunday, February 18, 2007 10:36 PM
Subject: [WanderlodgeForum] Coolant fan override switch
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
[Non-text portions of this message have been removed]
Coolant fan override switch - g_man1146 - 02-19-2007 04:24
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
>
> 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
>
Coolant fan override switch - David Brady - 02-19-2007 11:46
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
>
>> 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
>
>
>
>
>
>
[Non-text portions of this message have been removed]
Coolant fan override switch - ronmarabito2002 - 02-19-2007 13:46
I have not had a alarmstat failure on my 92, but I did on my 83PT40.
It definitely failed into high speed fan mode.
R.E. (Ron) Marabito, Dallas, TX 92WB40
--- In WanderlodgeForum@yahoogroups.com, "Leroy Eckert"
>
>
>
> This is exactly how my system works. I would think yours is similar.
> 1.With the fan override off and chassis a/c off the fan will spool
between approx 400x600 RPM. This continues until the temperature
reaches 195 degrees, (190 degrees now in my coach) then an alarmstat
turns the fan to high speed approx. 1800 RPM. The alarmstat operates
in an 8 to10 degree range, therefore cycling the fan from idle to
high mode over and over again, hence the cycling you may see on the
engine water temperature gauge. ( you will not see the cycling with
the chassis a/c on.) you may not see cycling in this configuration in
hot temperatures or while climbing hills.
>
> 2. Fan override off, and chassis a/c on: When the chassis a/c
switch is turned on( either pilot or co-pilot) the fan goes into high
mode, stays in high mode until the a/c switch is turned off. This
takes the fan override and the alarmstat out of the system, and
provides additional continuous cooling air for the condenser. My
condenser covers the top half of the radiator. Earlier models a/c
condenser are on the roof, cooled by electric fans.
>
> 3. Fan override on, chassis a/c off. Operates the same as item 2.
except the fan override switch has now taken the Alarmstat out of the
system. Using this switch in winter in my coach holds the engine
water temperature at engine thermostat value approx. 170-175. I
expect to see continuous 190 or less in summer in this configuration.
>
> 4. When my alarmstat failed/or became intermittent I experienced
creeping heat. I'm told that alarmstat failure is suppose to default
to fan high mode. I have not verified that.
>
> 4. So you see, Bluebirds engineers forced our coaches to run on the
high side of the DD specified range ( 170-210max, alarmed at 215
degrees: Ref: 13.12 DD Service Manual Pg. 13-48) by specifying the
195 degree alarmstat. Presumably, the thinking is that high fan RPM
robs power so the higher you run the temperature the less fan
activity. Unfortunately, that simply isn't the case because once the
195 degree temperature is attained the fan cycles continuously anyway.
It does the same thing in my bus using a 190 degree alarmstat ,
however, the benefit of the lower water temperature is lower engine
oil, tranny and retarder temperatures.
>
> When it gets hot, I intend to use my VMSpc to evaluate the
temperature differences resulting from my alarmstat value change from
195 degree to 190 degree. I fully expect to see a 6-8 percent
reduction in drivetrain component temperatures.
>
> The foregoing post has been documented with temperature values,
estimated outside air temps and road conditions while driving my 1990
WB-40 over the past 5 months.
>
> Leroy Eckert
> 1990 WB-40
> "Smoke N Mirrors"
>
>
>
>
>
>
> ----- Original Message -----
> From: David Brady
> To: WanderlodgeForum@yahoogroups.com
> Sent: Sunday, February 18, 2007 10:36 PM
> Subject: [WanderlodgeForum] Coolant fan override switch
>
>
> 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
>
>
>
>
> [Non-text portions of this message have been removed]
>
Coolant fan override switch - Gregory OConnor - 02-19-2007 14:02
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
> >
> >
> >
> >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>
Coolant fan override switch - Leroy Eckert - 02-19-2007 14:39
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
> >
> >
> >
> >
> >
> >
>
>
>
> [Non-text portions of this message have been removed]
>
[Non-text portions of this message have been removed]
Coolant fan override switch - g_man1146 - 02-19-2007 15:08
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"
>
> 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
> > >
> > >
> > >
> > >
> > >
> > >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>