Home » Public Forums » GMCnet » [GMCnet] Dash Blower inop
| [GMCnet] Dash Blower inop [message #368512] |
Thu, 20 January 2022 10:48  |
fbhtxak
Messages: 191
Registered: April 2006
Karma: 0
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Tom,
'Recommend you check the blower relay (it is under passenger side hood panel
at top right). " Emery's memo on the relays" that you mentioned may address
this - but if not...
When my blower would not start with dash control at "max", 'found that there
was no 12VDC at the blower motor - a result of no 12VDC from the relay.
After confirming that the low current side was OK (i.e.,relay coil ~ 0 Ohms
and 12VDC across it) and 12VDC supply to the high side , 'found 0 VDC high
side output. That suggested a problem with the relay contacts. Upon
disassembly, 'found high resistance across the contact points.
'Cleaned/filed points. 'Relay then sent 12VDC to blower motor, which then
operated normally.
Jim K. can probably supply that relay if you find that is defective and
don't want to attempt to repair it.
Fred
Fred Hudspeth
1978 Royale (TZE 368V101335) - Tyler, TX
1982 Airstream Excella (motorhome) - Cooper Landing, Alaska
Date: Wed, 19 Jan 2022 17:55:07 -0700
From:
Subject: [GMCnet] Dash Blower inop
To: gmclist@list.gmcnet.org
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Content-Type: text/plain; charset="utf-8"
Good evening guys and gals,
My dash environmental controls are inop. I am going to start trouble
shooting tomorrow night. I got Ken H's memo on the blower ground and Emery's
memo on the relays. Is there any thing else that is a normal failure item in
the HVAC system? I'm looking to address the common items in an attempt to
save time. The coach is a 1977, 23', Birchaven, 455 C.I.D.
Thanks in advance,
Tom K.
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| Re: [GMCnet] Dash Blower inop [message #368513 is a reply to message #368512] |
Thu, 20 January 2022 11:12  |
Tom Katzenberger
Messages: 399
Registered: June 2019
Location: Kingsville, MD
Karma: 4
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Fred,
Thank you so much. I will put this in the front of the inspection list. I do have some spare components from a couple of other coachs I have for parts.
Thanks again and stay healthy,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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| [GMCnet] Re: Dash Blower inop [message #368514 is a reply to message #368513] |
Thu, 20 January 2022 12:18 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Don't forget, that relay gets its secondary power from the engine
alternator. Your engine must be running before the fan will run on high
speed. If none of the speeds work, then it can only be the fan ground or
the speed controller in the driver's side of the heater box.
Jim Hupy
Salem, Oregon
On Thu, Jan 20, 2022, 9:12 AM wrote:
> Fred,
>
> Thank you so much. I will put this in the front of the inspection list. I
> do have some spare components from a couple of other coachs I have for
> parts.
>
> Thanks again and stay healthy,
> Tom K.
> --
> Tom & Oki Katzenberger,
> Kingsville, Maryland,
> 1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control,
> Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee
> Ignition
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: [GMCnet] Dash Blower inop [message #368520 is a reply to message #368512] |
Thu, 20 January 2022 18:47 |
Tom Katzenberger
Messages: 399
Registered: June 2019
Location: Kingsville, MD
Karma: 4
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Senior Member |
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Gentelmen,
I have power at the fuse panel and both sides of the heater fuse. I switched blower relays with a known operating blower relay. I by-passed the delay relay. I have no power at the fan speed selector or the newly switched out relay.
The fan does blow on low when the yellow wire is re-connected on the driver side low speed plug. I disabled the yellow wire in order to have the fan shut off when the selector is in the off position.
I guess I now know the blower is operating and grounded. I believe the relay is good.
Any additional thoughts and/or ideas are welcome?
I look forward to any suggestions.
Take care,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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| [GMCnet] Re: Dash Blower inop [message #368522 is a reply to message #368520] |
Fri, 21 January 2022 08:10 |
Dave Stragand
Messages: 307
Registered: October 2017
Karma: 0
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Tom,
I found John Watkins' presentation on HVAC troubleshooting to be a great resource. Here's the link:
https://www.gmcmi.com/wp-content/uploads/2018/04/GMCMH-AC-Control.pdf
The Road Knows…….. Heat/AC Dash Control and Vacuum Controls
The objective of this session is to…provide a through understanding of the dash Heat/ AC controls and how that knowledge can be used to help in troubleshooting. •To familiarize you with how the factory intended the Heat/AC control systems were
www.gmcmi.com
-Dave
1978 Transmode near Pittsburgh
________________________________
From: tomkatz3@comcast.net
Sent: Thursday, January 20, 2022 7:47 PM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Re: Dash Blower inop
Gentelmen,
I have power at the fuse panel and both sides of the heater fuse. I switched blower relays with a known operating blower relay. I by-passed the delay
relay. I have no power at the fan speed selector or the newly switched out relay.
The fan does blow on low when the yellow wire is re-connected on the driver side low speed plug. I disabled the yellow wire in order to have the fan
shut off when the selector is in the off position.
I guess I now know the blower is operating and grounded. I believe the relay is good.
Any additional thoughts and/or ideas are welcome?
I look forward to any suggestions.
Take care,
Tom K.
--
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee
Ignition
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1978 Transmode (403)
Pittsburgh, PA
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| Re: [GMCnet] Dash Blower inop [message #368524 is a reply to message #368512] |
Fri, 21 January 2022 18:45 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Dave, thanks for posting that link. I was at the seminar, but did not get that handout. It brings together things that are widely dispersed in the manuals, and will be very helpful.
JohnS
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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| Re: [GMCnet] Dash Blower inop [message #368525 is a reply to message #368512] |
Sat, 22 January 2022 07:58 |
Tom Katzenberger
Messages: 399
Registered: June 2019
Location: Kingsville, MD
Karma: 4
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Senior Member |
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Dave,
Thank you. I will continue trouble shooting today.
Take care,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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| Re: [GMCnet] Dash Blower inop [message #368526 is a reply to message #368512] |
Sat, 22 January 2022 08:53 |
Tom Katzenberger
Messages: 399
Registered: June 2019
Location: Kingsville, MD
Karma: 4
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Senior Member |
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Guys,
Thank you all!!
Using all the tools you guys provided, I traced the problem to the A/C Select Switch.
I want to share the solution for others who will travel down this path. Power went into the A/C Select Switch and did not come out when I bypassed the A/C Select Switch with a pig tail the fan speeds worked beautifully. I pulled the switch and replaced with a switch from a donner coach and all works great. I will clean and repair the old switch for the next 40 year repair.
Again, I want to thank everyone for all there help and support!!!
Take care and stay healthy!!
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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| Re: [GMCnet] Dash Blower inop [message #368528 is a reply to message #368512] |
Sat, 22 January 2022 16:57 |
Tom Katzenberger
Messages: 399
Registered: June 2019
Location: Kingsville, MD
Karma: 4
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Senior Member |
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Matt,
No worries. It is because of others and there sharing that I am able to more easily repair my coach. The thanks goes to all those who preceded me.
Take care,
Tom K.
Tom & Oki Katzenberger,
Kingsville, Maryland,
1977 23' Birchaven, 455 C.I.D., Micro Level, Howell EBL-EFI Spark Control, Macerator, York Air Compressor, 6 Wheel Disc, Quadra Bag, Onan W/Bovee Ignition
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