| Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73? [message #321814] |
Tue, 08 August 2017 16:52  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Most of these coach dashes are held together by bailing wire and dum-dum
putty regardless of what year model they are. They all squeak and rattle,
the vacuum doors are non functioning or the felt flap seals are missing or
deteriorated so bad that they leak badly. Combine that with dash controls
and vacuum hoses that are in poor shape, and you get the picture. The
heat/defrost/Air conditioning has deteriorated to the point of non
functioning. The fix???? Rip it all out and rebuild it all. Not a job for
the faint of heart. Band-Aids won't work here, neither will mickey mouse
fixes. Spend some money and do it the best way possible. You won't regret
it.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Aug 8, 2017 2:29 PM, "Jon Roche" wrote:
I could be wrong, but it is not just the external hvac box that is
different, but the ducting in the dash. I dont think it would be feasable
without destroying the dash and rebuilding.
Look at the write up tom pryor just had on the forum adding a dual
fan/blower to fix the hvac problems. I think he has something with that
and am
planning on doing that to my 75.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
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| Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73? [message #321815 is a reply to message #321814] |
Tue, 08 August 2017 17:11  |
Sammy Williams
Messages: 522
Registered: August 2010
Karma: -2
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Senior Member |
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Contact either of the Jims or Vintage Air. :) All 3 of them make excellent
fixes for the GMC dash HVAC.
Sammy
On Tue, Aug 8, 2017 at 4:52 PM, James Hupy wrote:
> Most of these coach dashes are held together by bailing wire and dum-dum
> putty regardless of what year model they are. They all squeak and rattle,
> the vacuum doors are non functioning or the felt flap seals are missing or
> deteriorated so bad that they leak badly. Combine that with dash controls
> and vacuum hoses that are in poor shape, and you get the picture. The
> heat/defrost/Air conditioning has deteriorated to the point of non
> functioning. The fix???? Rip it all out and rebuild it all. Not a job for
> the faint of heart. Band-Aids won't work here, neither will mickey mouse
> fixes. Spend some money and do it the best way possible. You won't regret
> it.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Aug 8, 2017 2:29 PM, "Jon Roche" wrote:
>
> I could be wrong, but it is not just the external hvac box that is
> different, but the ducting in the dash. I dont think it would be feasable
> without destroying the dash and rebuilding.
>
> Look at the write up tom pryor just had on the forum adding a dual
> fan/blower to fix the hvac problems. I think he has something with that
> and am
> planning on doing that to my 75.
>
>
> --
> Jon Roche
> 75 palm beach
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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>
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| Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73? [message #321820 is a reply to message #321815] |
Tue, 08 August 2017 18:01 |
 |
USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
I have an auxiliary under dash unit built by Vintage Air in Double Trouble and it provides heaps of extra cooling and keeps the
cockpit area comfortable; however, it has two downsides:
1) the vents will not direct cooling airflow directly onto the driver or passenger.
2) the twin 3 inch squirrel cage blowers on a single motor turns very fast to move the airflow and is noisy.
I intend to replace it with a mid 1960's Mustang under dash unit which has twin 5 inch squirrel cage blowers turns slower and is
much quieter.
They turn up on eBay quite regularly:
Tiny URL: http://tinyurl.com/y9ayvpa9
Full URL:
http://www.ebay.com/itm/1964-66-Ford-Falcon-Mustang-underdash-A-C-air-conditioning-unit-blower-works-/202012284935?hash=item2f08ded8
07:g:JPEAAOSwAr9Zh3K~&vxp=mtr
Note the size of the blowers!
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Sammy Williams
Sent: Wednesday, August 9, 2017 8:12 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73?
Contact either of the Jims or Vintage Air. :) All 3 of them make excellent
fixes for the GMC dash HVAC.
Sammy
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73? [message #321874 is a reply to message #321872] |
Wed, 09 August 2017 23:36 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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I have never installed a 77'78 in another model, but I know you'll need to
also replace the control panel.
On Wed, Aug 9, 2017 at 7:22 PM, KB wrote:
> For grins, I drew up some diagrams of 73/74, 75/76, and 77/78 hvac boxes
> and ducts that I've seen.
> It's not to scale and I don't have some of the angles right (eg the heater
> core mounted at an angle)
> but it should give an idea of the changes and airflow:
> http://www.gmcmhphotos.com/photos/original-details/
> p63520-hvac-air-conditioner-ac-heater-evaporator-box-changes.html
>
> The "Separating Hot from Cold" article by Jay Brand mostly focuses on the
> 77/78 and is a little misleading
> for prior years because the dash ducting is completely different.
>
> Karen
> 1975 26'
>
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: [GMCnet] Anyone ever put a 78 dash heater/AC in a 73? [message #321896 is a reply to message #321895] |
Thu, 10 August 2017 12:17 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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Nice job, Karen & very helpful. I am trying to figure out what to do to the stretch... Buskirk put in some different ducting, but it is just a relocation of the 78 outlets. We do need more air! I am looking at doing the mod outlined by Tom Pryor, but do not have it clear how the 78 extra heater outlet under the dash will fit with that mod.
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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