Home » Public Forums » GMCnet » I'm an idiot
| I'm an idiot [message #201830] |
Sat, 16 March 2013 16:50  |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
Karma: 7
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Where in tarnation is the blower fuse?
It does not appear to be in the fuse box...
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| Re: I'm an idiot [message #201833 is a reply to message #201830] |
Sat, 16 March 2013 17:32  |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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| Quote: |
Where in tarnation is the blower fuse?
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The heater/ac fan motor fuse is a 25amp fuse in the fuse block that is only hot with the ignition switch in the on position.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: I'm an idiot [message #201837 is a reply to message #201830] |
Sat, 16 March 2013 17:59 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Sir: most blower motor problems is the ground wire going to it.
| Joe Weir wrote on Sat, 16 March 2013 17:50 |
Where in tarnation is the blower fuse?
It does not appear to be in the fuse box...
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C. Boyd
76 Crestmont
East Tennessee
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| Re: I'm an idiot [message #201873 is a reply to message #201837] |
Sat, 16 March 2013 21:20 |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
Karma: 7
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Senior Member |
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Thanks i will check both those. Well, the radiator has been replaced, so maybe we disconnected the ground.
Took it out today for a road test to test the new radiator, or rather our installation of the new radiator. Ran it about 20 miles out on the interstate. No leaks, hurrah.
Would have been nicer with the ac fan blowing, it was warm today.
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
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| Re: I'm an idiot [message #201881 is a reply to message #201830] |
Sat, 16 March 2013 22:50 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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My coach had the same symptom when I bought it, but it turned out to be just a flaky connection on the back of the fuse block. It's pretty easy to trace it all out (nice having access to the blower motor without getting into a contortionist position).
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: I'm an idiot [message #201887 is a reply to message #201830] |
Sun, 17 March 2013 02:50 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Hi Joe:
There are actually two fuses used in the blower circuits.
Here is a picture of the fuse block behind the Glove compartment You need to look for the heater controls fuse (25 Amp) These are for the low speed stages of the blower. http://www.gmcmhphotos.com/photos/discussion-photos/p48075-fuse-panel.html
The second fuse is used in the High Speed Stages of the blower. The relay will connect full charging voltage to the blower when high speed is needed, and the voltage source wire needs to be fused. Look for it using the information here.
http://www.gmcmhphotos.com/photos/discussion-photos/p48078-fan-blower-control.html
In this picture the pigtail is disconnected (See White line) and shown in another picture. Here is what it looks like.
http://www.gmcmhphotos.com/photos/discussion-photos/p48077-fan-pigtail-with-capacitor.html
http://www.gmcmhphotos.com/photos/discussion-photos/p48080-flow-thru-capacitor.html
A pigtail in this condition needs to be serviced for optimum blower operation. There are other possible problems of course, but these ones are not always so easy to find.
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: I'm an idiot [message #201899 is a reply to message #201873] |
Sun, 17 March 2013 09:33 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
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Senior Member |
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http://www.gmcmhphotos.com/photos/member-galleries/p42831-dsc03822-a.html
| Joe Weir wrote on Sat, 16 March 2013 22:20 |
Thanks i will check both those. Well, the radiator has been replaced, so maybe we disconnected the ground.
Took it out today for a road test to test the new radiator, or rather our installation of the new radiator. Ran it about 20 miles out on the interstate. No leaks, hurrah.
Would have been nicer with the ac fan blowing, it was warm today.
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C. Boyd
76 Crestmont
East Tennessee
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| Re: [GMCnet] I'm an idiot [message #201907 is a reply to message #201899] |
Sun, 17 March 2013 10:32 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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The screw shown in Chuck's link is the only ground for the blower motor.
It's threaded into the plastic blower housing so its only electrical
contact is through the head of the screw. It's almost mandatory to use a
star washer beneath that head, preferable with an electrically conductive
paste, like Nooxid. Without that, intermittent problems are almost
guaranteed.
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
On Sun, Mar 17, 2013 at 10:33 AM, Charles Boyd wrote:
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> http://www.gmcmhphotos.com/photos/member-galleries/p42831-dsc03822-a.html
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] I'm an idiot [message #201955 is a reply to message #201907] |
Sun, 17 March 2013 16:48 |
Joe Weir
Messages: 769
Registered: February 2013
Location: Columbia, SC
Karma: 7
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Senior Member |
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Thanks for the help and the photos.
That helped pinpoint the issue. Observe the wire in the foreground which is missing a capacitor and is connected to...nothing!
The blower worked on the test drive, so I must have disconnected it. I just can't find the other end of it.
and then there is this bit of foolishness:
I'm just hazarding a wild guess, but these are supposed to be connected? Why were they cut would be the big question.
76 Birchaven - "Wicked Mistress" - New engine, trans, alum radiator, brakes, Sully airbags, fuel lines, seats, adult beverage center... those Coachmen guys were really thinking about us second hand owners by including that beverage center...
Columbia, SC.
[Updated on: Sun, 17 March 2013 17:38] Report message to a moderator |
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| Re: [GMCnet] I'm an idiot [message #201984 is a reply to message #201955] |
Sun, 17 March 2013 22:45 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Joe Weir wrote on Sun, 17 March 2013 14:48 |
Thanks for the help and the photos.
That helped pinpoint the issue. Observe the wire in the foreground which is missing a capacitor and is connected to...nothing!
<http://i23.photobucket.com/albums/b395/DarkJethro/photo.jpg>
The blower worked on the test drive, so I must have disconnected it. I just can't find the other end of it.
and then there is this bit of foolishness:
<http://i23.photobucket.com/albums/b395/DarkJethro/photo1.jpg>
I'm just hazarding a wild guess, but these are supposed to be connected? Why were they cut would be the big question.
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The second issue first: Other than the early coaches, there wasn't an "off" position for the fan. The yellow wire is the low speed for the fan. Cutting it makes the lowest setting into an "fan off" position. (Looks like a PO has done this.) It is also a good place to tap accessory power. I used it for the vacuum pump for the brakes on my '78.
The first issue: The power for the high speed fan comes from the alternator side of the isolator. This gives it a more voltage and makes the fan run faster but only when the engine is running. Follow the wire connected to the center post of the isolator and you should find where the power is tapped off the line.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] I'm an idiot [message #201986 is a reply to message #201984] |
Sun, 17 March 2013 23:17 |
mickeysss
Messages: 1476
Registered: January 2012
Karma: 0
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Senior Member |
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Thanks for this picture of the yellow blower wire!
So the yellow wire is low speed that goes to my fuel pump under the radiator now, this wire means the fan is on
low all the time that wears out the blower motor for no reason at all. I should just cut it in my 77 palm beach then
put my fuel pump back to the tank switch to the rear frame out side and reconnect the fuel hose back to the
mech. pump up front. I will put the yellow on my vacuum pump that i have from jimK and use a bent hose
like robM states from the pump to the big booster hole. That will give the pump it's own wire and keep it fully
charged and not supporting the fan which is safer for the brakes. i have to drive in the big hills.
i finally get it now. for that design. thank you for the yellow wire picture. Thank you if anyone has another idea to
help me get this system together i appreciate it.
best regards
mickey :-)
77 palm beach
anaheim ca.
you may have saved my life with this design.
These little designs really make a difference.
On Mar 17, 2013, at 8:45 PM, Mike Miller wrote:
>
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> Joe Weir wrote on Sun, 17 March 2013 14:48
>> Thanks for the help and the photos.
>>
>> That helped pinpoint the issue. Observe the wire in the foreground which is missing a capacitor and is connected to...nothing!
>>
>> <http://i23.photobucket.com/albums/b395/DarkJethro/photo.jpg>
>>
>> The blower worked on the test drive, so I must have disconnected it. I just can't find the other end of it.
>>
>> and then there is this bit of foolishness:
>>
>> <http://i23.photobucket.com/albums/b395/DarkJethro/photo1.jpg>
>>
>> I'm just hazarding a wild guess, but these are supposed to be connected? Why were they cut would be the big question.
>
>
> The second issue first: Other than the early coaches, there wasn't an "off" position for the fan. The yellow wire is the low speed for the fan. Cutting it makes the lowest setting into an "fan off" position. (Looks like a PO has done this.) It is also a good place to tap accessory power. I used it for the vacuum pump for the brakes on my '78.
>
> The first issue: The power for the high speed fan comes from the alternator side of the isolator. This gives it a more voltage and makes the fan run faster but only when the engine is running. Follow the wire connected to the center post of the isolator and you should find where the power is tapped off the line.
>
>
> --
> Mike Miller -- Hillsboro, OR -- on the Black list
> (#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
> http://m000035.blogspot.com
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| Re: I'm an idiot [message #201988 is a reply to message #201830] |
Mon, 18 March 2013 00:55 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Joe:
For the first issue of where to put the wire from the blower relay, here is a picture of the blower fan and where to place the pigtail. It can be quite easy to pull off sometimes especially if it had been overheated at some time. If it is not snug, service the connector or replace it. If you do not have a radio option your pigtail will not have the capacitor. (But it might have broken like the one I showed earlier and was removed) I repaired mine and will upload pictures in the next few days
http://www.gmcmhphotos.com/photos/discussion-photos/p48084-blower-motor-pigtail.html
The picture of the cut wire is the harness to the resistor network for the lower speeds of the blower motor. The yellow is for the lowest speed. As others have said it may have been cut because you may not have an "Off on your fan switch.
You can reconnect it, if you would like to have low speed for the fan.
(IMHO) Another auxiluary switch, in another location would be a better option to turn off the fan. That would allow the benifits of the fan being able to operate on low speed. I like a low speed that creates a gentle air flow.
I've simplified a wiring diagram for the blower speed circuit to help with any diagnostics.
http://www.gmcmhphotos.com/photos/discussion-photos/p48085-blower-control.html
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: I'm an idiot [message #201990 is a reply to message #201830] |
Mon, 18 March 2013 01:37 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Mickey and All:
I'm really concerned for you!!!
I'm shuddering at you suggestions of picking some random wire color to power your safety devices such as a Vacuum pump for Brakes and for your fuel pumps!!
I really feel anyone doing an electrical installation should know exactly what they are tapping into, and the consequenses of doing so. (Not every tapping is bad, but we only know that if we know all the details)
For this specific example I have a concern. My experience is that Blower motors blowing fuses is not uncommon. By adding another electric motor, or another high load item (or any other item for that matter) to the heating circuit we increase the likelyhood of blowing the fuse and render you safety device ineffective. Adding a larger fuse is not an option!!!
Creating an appropriate circuit, from an appropriate source, with appropiate wire sizes and fuseing is the only way to create a fire resistant, dependable system.
It is really important that you study wiring diagrams to help avoid some problems. Helps fix them too!!!
Be safe everyone!!!
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: I'm an idiot [message #201993 is a reply to message #201990] |
Mon, 18 March 2013 04:07 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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John, That 14 ga yellow wire removed from the blower motor resistor gets it's power from the 25 amp heater fuse. Since it is there and readily available, many of us have used it to power the vacuum pump. I have my vacuum pump attached that way. I have never blown that fuse in the many years it has been that way so I assume the combined power used by the slower speeds of the fan plus the vacuum pump are below the 25 amp fuse rating. I honestly have never measured the combined current draw.
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: I'm an idiot [message #201995 is a reply to message #201993] |
Mon, 18 March 2013 04:28 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Ken Burton wrote on Mon, 18 March 2013 02:07 |
.. Since it is there and readily available, many of us have used it to power the vacuum pump. I have my vacuum pump attached that way. I have never blown that fuse in the many years it has been that way so I assume the combined power used by the slower speeds of the fan plus the vacuum pump are below the 25 amp fuse rating. I honestly have never measured the combined current draw. ...
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The vacuum pump I use is POWERED by a direct line to the battery. (With a self reseting CB.) The accessory comes from the yellow wire in question and is used only for switching proposes in the pump.
But yes, if the fan fuse is blown, I'd loose the vacuum pump... a BACK-UP "safety" system. While I haven't blown the fuse... it might be something to think about. For my next installation if nothing else!
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: I'm an idiot [message #202002 is a reply to message #201995] |
Mon, 18 March 2013 06:49 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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My solution for use of the yellow wire. I use the yellow wire to pull in a typical automobile 12v relay. The relay's contacts make and break a much heavier gauge wire, directly connected to the engine battery. I have a 20 amp breaker on that line. Really reduces the load on the yellow wire.
I remember seeing at one International a coach had an entire fleet of these relays.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: I'm an idiot [message #202016 is a reply to message #201830] |
Mon, 18 March 2013 10:01 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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Ken
Re. | Quote: |
John, That 14 ga yellow wire removed from the blower motor resistor gets it's power from the 25 amp heater fuse. Since it is there and readily available, many of us have used it to power the vacuum pump. I have my vacuum pump attached that way. I have never blown that fuse in the many years it has been that way so I assume the combined power used by the slower speeds of the fan plus the vacuum pump are below the 25 amp fuse rating. I honestly have never measured the combined current draw.
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My concern is that it is very common for the bushings in the blower motor to dry and the extra load increases current draw creating a POTENTIAL problem. If one of the bushings sieze, a locked rotor is basically a short thus blowing the fuse. If the fuse does not blow from that alone, the additional load from other high load devices may bring it over the top. It is also very common for connectors in the blower system to overheat, and then corrode, which cause problems of high voltage drop. In other words the blower circuit is more prone to risk than a dedicated installation. In this case the items in this circuit all depend on the health of the blower motor, that is undependable to start with.
(Hmmm?? The engine won't run because the blower seized disabling the fuel pump). ( The brake safety back up system is dependant on the health of the heating system. )
I realize that these things may need a cascade of incidents to become hazardous. However: I believe that by leaving the blower circuit out of the equation would provide a more robust reliable installation.
Best Regards
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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| Re: [GMCnet] I'm an idiot [message #202019 is a reply to message #202016] |
Mon, 18 March 2013 10:18 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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But considered this, pilgrim. when you add additional conductors along a
sometimes poorly supported path, with more switches and fuse holders, does
it make the total machine more reliable, or less reliable. I think,
statistically speaking, that the simpler machine is the more reliable
machine. Parts omitted cost nothing and cause no service problems. The
K.I.S.S. Principle applies 100% of the time. Just sayin'. (grin)
Jim Hupy
Salem, Or
78 Gmc Royale 403 ( with the yellow wire disconnected, I hate fans that
always run.)
On Mar 18, 2013 8:01 AM, "John Heslinga" <rbeeper@hotmail.com> wrote:
>
>
> Ken
>
> Re. Quote:
> > John, That 14 ga yellow wire removed from the blower motor resistor gets
> it's power from the 25 amp heater fuse. Since it is there and readily
> available, many of us have used it to power the vacuum pump. I have my
> vacuum pump attached that way. I have never blown that fuse in the many
> years it has been that way so I assume the combined power used by the
> slower speeds of the fan plus the vacuum pump are below the 25 amp fuse
> rating. I honestly have never measured the combined current draw.
>
>
> My concern is that it is very common for the bushings in the blower motor
> to dry and the extra load increases current draw creating a POTENTIAL
> problem. If one of the bushings sieze, a locked rotor is basically a short
> thus blowing the fuse. If the fuse does not blow from that alone, the
> additional load from other high load devices may bring it over the top. It
> is also very common for connectors in the blower system to overheat, and
> then corrode, which cause problems of high voltage drop. In other words
> the blower circuit is more prone to risk than a dedicated installation.
> In this case the items in this circuit all depend on the health of the
> blower motor, that is undependable to start with.
>
> (Hmmm?? The engine won't run because the blower seized disabling the
> fuel pump). ( The brake safety back up system is dependant on the health of
> the heating system. )
>
> I realize that these things may need a cascade of incidents to become
> hazardous. However: I believe that by leaving the blower circuit out of the
> equation would provide a more robust reliable installation.
>
> Best Regards
> --
> John and Cathie Heslinga
> 1974 Canyonlands 260
> TC4W "Too Cool For Words"
> Retirement Projects Galore
> Edmonton, Alberta
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: I'm an idiot [message #202027 is a reply to message #201830] |
Mon, 18 March 2013 11:13 |
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John Heslinga
Messages: 632
Registered: February 2011
Location: Edmonton, Alberta, Canada
Karma: 4
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Senior Member |
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James:
KISS. That's exactly what I'm saying. The heating circuit has too many things that can cause a problem.
A wire coming directly from the ignition buss through a breaker or fuse to the vacuum pump is safer and a simpler circuit.
The only thing that was simple about the "yellow wire", was for the installer.
John and Cathie Heslinga
1974 Canyonlands 260
455, Manny tranny and 1 ton, 3:70 LS,
Red Seal Journeyman, DTE, BEd. MEd.
Edmonton, Alberta
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