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| One Speed Blower Fan [message #219964] |
Mon, 26 August 2013 08:25  |
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WD0AFQ
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Registered: November 2004
Location: Dexter, Mo.
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Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: One Speed Blower Fan [message #219975 is a reply to message #219964] |
Mon, 26 August 2013 09:09  |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
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That's the weirdest thing I've ever heard. The only electrical to the trans is the kickdown and I don't think you are using that much throttle. Could this be pinched wire from trans mount fail? Inspect the loom and check the blower resistor and connectors and same at hi blower relay.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: One Speed Blower Fan [message #219977 is a reply to message #219964] |
Mon, 26 August 2013 09:26 |
MikeT
Messages: 225
Registered: November 2009
Location: Marine City, Michigan
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Dan, I have the same problem. One speed on the fan, High, regardless of switch position, low, med or high.
Look forward to the solution.
Mike Thomas
Marine City, MI
77 ex Palm Beach
[Updated on: Mon, 26 August 2013 09:27] Report message to a moderator |
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| Re: One Speed Blower Fan [message #219978 is a reply to message #219977] |
Mon, 26 August 2013 09:34 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
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Perhaps the high speed fan relay is stuck closed. Would be the first place to look. For the other speeds, you might check the connector to the fan selector switch.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: One Speed Blower Fan [message #219980 is a reply to message #219964] |
Mon, 26 August 2013 09:42 |
Dennis S
Messages: 3046
Registered: November 2005
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| WD0AFQ wrote on Mon, 26 August 2013 08:25 |
Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
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Dan
Does your alternator charge in second gear?
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: One Speed Blower Fan [message #219985 is a reply to message #219980] |
Mon, 26 August 2013 11:02 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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| Dennis S wrote on Mon, 26 August 2013 09:42 |
| WD0AFQ wrote on Mon, 26 August 2013 08:25 |
Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
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Dan
Does your alternator charge in second gear?
Dennis
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Dennis, what do you mean? If it didn't I would notice a drop in voltage and/or a drop in positive current on my shunt fed amp meter. I have a new spare relay but really don't think that is the problem. I suspect the thing has been wired that way by PO because of a bad switch, and I have a spare one of those too. Just wondered if anyone had seen this before.
Thanks,
Dan
Counting days til Branson
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: One Speed Blower Fan [message #219987 is a reply to message #219985] |
Mon, 26 August 2013 11:17 |
Dennis S
Messages: 3046
Registered: November 2005
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| WD0AFQ wrote on Mon, 26 August 2013 11:02 |
| Dennis S wrote on Mon, 26 August 2013 09:42 |
| WD0AFQ wrote on Mon, 26 August 2013 08:25 |
Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
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Dan
Does your alternator charge in second gear?
Dennis
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Dennis, what do you mean? If it didn't I would notice a drop in voltage and/or a drop in positive current on my shunt fed amp meter. I have a new spare relay but really don't think that is the problem. I suspect the thing has been wired that way by PO because of a bad switch, and I have a spare one of those too. Just wondered if anyone had seen this before.
Thanks,
Dan
Counting days til Branson
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Dan
I was just thinking -- doesn't the high speed fan get it's feed directly from the alternator? That's why the fan won't (normally) run in high unless the engine is running.
So, if the fan stops in second I wondered if the alternator was still producing.
As you say, most likely some PO revision that will require you to trace the wiring.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: One Speed Blower Fan [message #219989 is a reply to message #219987] |
Mon, 26 August 2013 11:34 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Ok, y'all got me out and into the coach. With key on, no engine, low speed is very slow. 2nd, nothing, and high is high speed. Cut the engine on, low and third are high speed, nothing in second gear with the switch. So, someone has done some re wiring because high is high speed even with no alternator.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: One Speed Blower Fan [message #219993 is a reply to message #219964] |
Mon, 26 August 2013 12:33 |
A Hamilto
Messages: 4508
Registered: April 2011
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| WD0AFQ wrote on Mon, 26 August 2013 08:25 |
Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
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Dan,
If your fan operates depending on the gear the transmission is in, I have no idea.
If you are saying on the low setting it blows high, on the medium setting it does nothing, and on the high setting it blows high, then:
The wiring between the dash switch and the blower relay has been mucked up.
The fan wiring is pretty simple. On high the the connection goes from the switch contact through the blower relay, where the relay connects the fan motor directly to the alternator output. On medium and low, it goes from the switch contact to a resistor in the pack mounted to the blower box then the blower relay then to the fan motor. The resistor on the low speed is higher than the resistor on the medium speed.
http://www.gmcmhphotos.com/photos/data/2/medium/BlowerControlCkt.jpg
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| Re: One Speed Blower Fan [message #220000 is a reply to message #219993] |
Mon, 26 August 2013 13:11 |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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Senior Member |
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| A Hamilto wrote on Mon, 26 August 2013 12:33 |
| WD0AFQ wrote on Mon, 26 August 2013 08:25 |
Reading Kerry's post on moving brake light wire brought this to mind.
My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
Dan
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Dan,
If your fan operates depending on the gear the transmission is in, I have no idea.
If you are saying on the low setting it blows high, on the medium setting it does nothing, and on the high setting it blows high, then:
The wiring between the dash switch and the blower relay has been mucked up.
The fan wiring is pretty simple. On high the the connection goes from the switch contact through the blower relay, where the relay connects the fan motor directly to the alternator output. On medium and low, it goes from the switch contact to a resistor in the pack mounted to the blower box then the blower relay then to the fan motor. The resistor on the low speed is higher than the resistor on the medium speed.
http://www.gmcmhphotos.com/photos/data/2/medium/BlowerControlCkt.jpg
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Thanks. You are on track. Bad choice of words on my part. First, low. Second, medium. High, high speed on switch. Will study the schematic.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: One Speed Blower Fan [message #220001 is a reply to message #219989] |
Mon, 26 August 2013 13:22 |
A Hamilto
Messages: 4508
Registered: April 2011
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| WD0AFQ wrote on Mon, 26 August 2013 11:34 |
Ok, y'all got me out and into the coach. With key on, no engine, low speed is very slow. 2nd, nothing, and high is high speed. Cut the engine on, low and third are high speed, nothing in second gear with the switch. So, someone has done some re wiring because high is high speed even with no alternator.
Dan
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Here are some enhanced wiring diagrams of how the circuitry is supposed to work:
Lo Speed
http://www.gmcmhphotos.com/photos/electrical/p50599-low-speed-dash-fan-circuit-path.html
Medium Speed
http://www.gmcmhphotos.com/photos/electrical/p50600-medium-speed-dash-fan-circuit-path.html
High Speed
http://www.gmcmhphotos.com/photos/electrical/p50601-high-speed-dash-fan-circuit-path.html
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| Re: [GMCnet] One Speed Blower Fan [message #220006 is a reply to message #220000] |
Mon, 26 August 2013 14:20 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Dan
It can also be caused by a bad resistor pack in the heater box. The medium coil might be burned out and perhaps its shorted across the low coil.
Emery Stora
On Aug 26, 2013, at 12:11 PM, Dan Gregg wrote:
>
>
> A Hamilto wrote on Mon, 26 August 2013 12:33
>> WD0AFQ wrote on Mon, 26 August 2013 08:25
>>> Reading Kerry's post on moving brake light wire brought this to mind.
>>> My heater/AC switch blows only full speed. In first gear, it blows wide open. In second gear it does not blow. In high it blows full speed, just like in first gear. It has always been this way sine we have owned the coach, 2004. I have never worried enough to fix it. It's 74 coach and has "off". What should I be looking for?
>>> Dan
>> Dan,
>>
>> If your fan operates depending on the gear the transmission is in, I have no idea.
>>
>> If you are saying on the low setting it blows high, on the medium setting it does nothing, and on the high setting it blows high, then:
>>
>> The wiring between the dash switch and the blower relay has been mucked up.
>>
>> The fan wiring is pretty simple. On high the the connection goes from the switch contact through the blower relay, where the relay connects the fan motor directly to the alternator output. On medium and low, it goes from the switch contact to a resistor in the pack mounted to the blower box then the blower relay then to the fan motor. The resistor on the low speed is higher than the resistor on the medium speed.
>>
>> http://www.gmcmhphotos.com/photos/data/2/medium/BlowerControlCkt.jpg
>
> Thanks. You are on track. Bad choice of words on my part. First, low. Second, medium. High, high speed on switch. Will study the schematic.
> Dan
> --
> Dan & Teri Gregg
> Dexter, Mo.
>
> http://danandteri.blogspot.com/
>
>
>
>
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| Re: [GMCnet] One Speed Blower Fan [message #220007 is a reply to message #219989] |
Mon, 26 August 2013 14:24 |
emerystora
Messages: 4442
Registered: January 2004
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Dan
I know you have a 1974. I am not sure that GM wired the high speed to the alternator output with the relay. They might have -- I know they did in later models.
On my 1977 there is a MAX position which connects the alternator to it.
Emery Stora
On Aug 26, 2013, at 10:34 AM, Dan Gregg wrote:
>
>
> Ok, y'all got me out and into the coach. With key on, no engine, low speed is very slow. 2nd, nothing, and high is high speed. Cut the engine on, low and third are high speed, nothing in second gear with the switch. So, someone has done some re wiring because high is high speed even with no alternator.
> Dan
> --
> Dan & Teri Gregg
> Dexter, Mo.
>
> http://danandteri.blogspot.com/
>
>
>
>
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| Re: One Speed Blower Fan [message #220019 is a reply to message #219964] |
Mon, 26 August 2013 17:25 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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So nothing to do with the transmission?
Now we are back to normal insanity.
This can be fixed. Pull the fan resitor and inspect visually and with an Ohm meter. You can see where the coils are crimp welded to the prongs and you should have some low Ohms continuity across all the connections where there is a spring style resistor present. I'm not worried about the values so much as if they are intact. The dash switch sellects how many and which resistors are added into the circuit. And the resistors do get hot so don't burn your fingers, the air stream from the blower squirel cage cools it. The connectors on the resitor pack love to get wet, odxidize, add resitance and get hot and melt. Later GM went to the weatherpack type connectors.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: One Speed Blower Fan [message #220229 is a reply to message #220019] |
Wed, 28 August 2013 15:20 |
A Hamilto
Messages: 4508
Registered: April 2011
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Since Dan hasn't told us what he found, I will take another stab at explaining the fan speed control circuitry:
For the "schematically challenged" (colors are from the 1973 MM):
With everything OFF, there should be ZERO OHMS (or very small reading) between pins 1 (purple wire) and 2 (tan wire) of the blower relay (solenoid in "resting" position).
Then, with the ignition switch in the ACC position (engine not running):
With the fan speed selector on "LO", there should be 12VDC to pin 2 of the resistor pack on the blower box (yellow wire). There should be something less than 12VDC on pin 1 of the resistor pack on the blower box (tan wire). That same lower voltage should be present on pin 2 of the blower relay (tan wire), AND pin 1 of the blower relay (purple wire). The fan motor should have that voltage and be running.
With the fan speed selector on "MED", there should be 12VDC to pin 3 of the resistor pack on the blower box (light blue wire). There should be something less than 12VDC (but more than the reading on "LO") on pin 1 of the resistor pack on the blower box (tan wire). That same voltage should be present on pin 2 of the blower relay (tan wire), AND pin 1 of the blower relay (purple wire). The fan motor should be running faster than it was on "LO".
With the fan speed selector on "HI", there should be 12VDC on pin 4 of the blower relay (orange wire), and there should be ZERO OHMS (or very small reading) between pins 1 (purple wire) and 3 (red double white stripe wire) of the blower relay (solenoid in "energized" position).
When the engine is running, there should be alternator voltage at pins 1 and 3 of the blower relay, and the fan should be blowing high speed.
If it is not working that way, you have wires crossed, broken or disconnected, and/or dirty/corroded connectors, or bad resistors in the resistor pack, or a defective blower relay. Any "failed test" in the procedure should tell you what is not right.
[Updated on: Wed, 28 August 2013 16:12] Report message to a moderator |
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| Re: [GMCnet] One Speed Blower Fan [message #220319 is a reply to message #220229] |
Thu, 29 August 2013 11:08 |
Mr ERFisher
Messages: 7117
Registered: August 2005
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you mean these?
http://www.gmcmhphotos.com/photos/electrical/p50598-heater-and-dash-air-conditioner-wiring.html
gene
On Wed, Aug 28, 2013 at 1:20 PM, A. <markbb1@netzero.com> wrote:
>
>
> Since Dan hasn't told us what he found, I will take another stab at
> explaining the fan speed control circuitry:
>
> For the "schematically challenged" (colors are from the 1973 MM):
>
> With everything OFF, there should be ZERO OHMS (or very small reading)
> between pins 1 (purple wire) and 2 (tan wire) of the blower relay (solenoid
> in "resting" position).
>
> Then, with the ignition switch in the ACC position (engine not running):
>
> With the fan speed selector on "LO", there should be 12VDC to pin 2 of the
> resistor pack on the blower box (yellow wire). There should be something
> less than 12VDC on pin 1 of the resistor pack on the blower box (tan wire).
> That same lower voltage should be present on pin 2 of the blower relay
> (tan wire), AND pin 1 of the blower relay (purple wire). The fan motor
> should have that voltage and be running.
>
> With the fan speed selector on "MED", there should be 12VDC to pin 3 of
> the resistor pack on the blower box (light blue wire). There should be
> something less than 12VDC (but more than the reading on "LO") on pin 3 of
> the resistor pack on the blower box (tan wire). That same voltage should
> be present on pin 2 of the blower relay (tan wire), AND pin 1 of the blower
> relay (purple wire). The fan motor should be running faster than it was on
> "LO".
>
> With the fan speed selector on "HI", there should be 12VDC on pin 4 of the
> blower relay (orange wire), and there should be ZERO OHMS (or very small
> reading) between pins 1 (purple wire) and 3 (red double white stripe wire)
> of the blower relay (solenoid in "energized" position).
>
> When the engine is running, there should be alternator voltage at pins 1
> and 3 of the blower relay, and the fan should be blowing high speed.
>
> If it is not working that way, you have wires crossed, broken or
> disconnected, and/or dirty/corroded connectors, or bad resistors in the
> resistor pack, or a defective blower relay. Any "failed test" in the
> procedure should tell you what is not right.
> --
> '73 23' Sequoia For Camping
> '73 23' CanyonLands For Sale
> UA (Upper Alabama)
> "Time is money. If you use YOUR time, you get to keep YOUR money."
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--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] One Speed Blower Fan [message #220332 is a reply to message #220319] |
Thu, 29 August 2013 12:13 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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Yes. As far as "component count", there isn't much that can go wrong in the fan blower circuitry. The resistors or the relay (or the switch itself). PO wiring changes and loose/corroded connectors account for pretty much anything else.
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