Dash Air Conditioning Vents

S

SteveW

Active member
Nov 3, 2012
567
44
28
Greetings from Southern California !!

I'm about to take on a Dash Air Conditioning investigation / improvement project.

I'm aware of some of the options and am closely following the new dash AC systems being installed down at the Coop (Thanks for those postings Jim).

Has anyone retrofitted the newer model's under dash vents to a system that didn't have them? I'm envisioning that it'll require the creation of an
opening through the firewall and into the air box. And then the retrofittting of some sort of sheet metal panels to route airflow to the new exits.

Or is the addition of an underdash "Vintage Air" evaporator a better solution? How loud are these aux units?

And... might anyone have an underdash vent unit that you'd be willing to sell. I expect they're only available from donor coaches...

As always, thank you all for the wealth of information posted here and thank you in advance for your comments and suggestions.

Steve W
1973 23'
Southern California
 
The Max Air vents connect to the mixed air chamber. Conditioned air would divide based on relative resistance of upper and lower ducts. The '75-76 box
has an internal flap that directs all air to the Max Air vents when AC is selected. There's no existing opening to that chamber, so you'd have to make
a collar that joins the firewall with the HVAC box to connect the Max Air duct to the chamber.
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Steve,
The most effective A/C is when the inside air is recirculated.
Cooling the outside air initially is fine, but the cooling the inside air
which is cooler than the outside is what the Vintage Air unit does.Also the
blower has to work harder to pull in the outside air.

On Mon, May 7, 2018 at 10:21 PM, Bill Van Vlack
wrote:

> The Max Air vents connect to the mixed air chamber. Conditioned air would
> divide based on relative resistance of upper and lower ducts. The '75-76 box
> has an internal flap that directs all air to the Max Air vents when AC is
> selected. There's no existing opening to that chamber, so you'd have to make
> a collar that joins the firewall with the HVAC box to connect the Max Air
> duct to the chamber.
> --
> Bill Van Vlack
> '76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath,
> Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o
> mid
> November 2015.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
Get hold of Tom {ryor and ask him for the pictures of his mod.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
I suspect the Vintage Air system is the better way to go. I have the under dash plenum and unmodified it's weak. I have to dig in and make the modifications to help it as best I can, but I think the Vintage Air systems would be much more effective.

Larry Davick
Fremont, California
A Mystery Machine
'76 (ish) Palm Beach

>
>
> Greetings from Southern California !!
>
> I'm about to take on a Dash Air Conditioning investigation / improvement project.
>
> I'm aware of some of the options and am closely following the new dash AC systems being installed down at the Coop (Thanks for those postings Jim).
>
> Has anyone retrofitted the newer model's under dash vents to a system that didn't have them? I'm envisioning that it'll require the creation of an
> opening through the firewall and into the air box. And then the retrofittting of some sort of sheet metal panels to route airflow to the new exits.
>
> Or is the addition of an underdash "Vintage Air" evaporator a better solution? How loud are these aux units?
>
> And... might anyone have an underdash vent unit that you'd be willing to sell. I expect they're only available from donor coaches...
>
> As always, thank you all for the wealth of information posted here and thank you in advance for your comments and suggestions.
>
> Steve W
> 1973 23'
> Southern California
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
G'day,

I have a Vintage Air type system in Double Trouble, unfortunately it is noisy. I attribute that to the fact that the squirrel cage
blower is 3 1/2 inch in diameter and to move air it has to spin FAST.

I discovered that the mid 1960's Ford Mustangs had A/C as an option and the squirrel cage is 5" in diameter. It turns slower and
moves as much if not more air than the Vintage Air. Re-pops are available, however, I don't know what diameter squirrel cage they
have.

Regards,
Rob M.
The Pedantic Mechanic
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] On Behalf Of Larry Davick
Sent: Tuesday, May 8, 2018 12:47 PM
To: gmclist
Subject: Re: [GMCnet] Dash Air Conditioning Vents

I suspect the Vintage Air system is the better way to go. I have the under dash plenum and unmodified it's weak. I have to dig in
and make the modifications to help it as best I can, but I think the Vintage Air systems would be much more effective.

Larry Davick
Fremont, California
A Mystery Machine
'76 (ish) Palm Beach

>
>
> Greetings from Southern California !!
>
> I'm about to take on a Dash Air Conditioning investigation / improvement project.
>
> I'm aware of some of the options and am closely following the new dash AC systems being installed down at the Coop (Thanks for
those postings Jim).
>
> Has anyone retrofitted the newer model's under dash vents to a system that didn't have them? I'm envisioning that it'll require
the creation of an
> opening through the firewall and into the air box. And then the retrofittting of some sort of sheet metal panels to route
airflow to the new exits.
>
> Or is the addition of an underdash "Vintage Air" evaporator a better solution? How loud are these aux units?
>
> And... might anyone have an underdash vent unit that you'd be willing to sell. I expect they're only available from donor
coaches...
>
> As always, thank you all for the wealth of information posted here and thank you in advance for your comments and suggestions.
>
> Steve W
> 1973 23'
> Southern California
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
You may want to take a look at the modification that I employed in my 77
23B. Look at images as shown on: http://www.gmcmhphotos
.com/photos/g7068-i-need-more-air.html.

My coach is still in the Barn, But I believe Karen Bradley has embraced the
idea and plans to modify her Coach. In Brief the Steps are as follows:

1. Cut a hole in the floor as shown in the Images just below the dash.
2. Cut a hole in the HVAC box that is now Accessible.
3. Construct a Plenum as shown in the drawing out of any sheet metal,
aluminum or fiberglass sheet. I used fiberglass sheet and West system
Resin..
4. Use double face rubber tape and secure Plenum to HVAC box and
Floor........follow with self tapping screws or pop rivets.
5. Remove the OEM HVAC fan and discard it. COVER THE HOLE WITH SHEET
METAL OR ALUMINUM.
6. Use the Same wiring scheme as used on the OEM Fan when installing the
a new dual stage Centrifugal Fan on the Floor. It has about 30% more CFM
than the OEM Fan.

WITH THIS MODIFICATION NOTHING CHANGES EXCEPT THE AIR FLOW IS DIRECTED THRU
THE HVAC BOX........IT DOES NOT HAVE TO CHANGE DIRECTIONS MULTIPLE TIMES TO
ESCAPE TO THE DASH AND UNDER DASH VENTING. IN ADDITION THE DASH HVAC
CONTROLS ARE NOT DISTURBED. THE DOWN SIDE IS THAT YOU DO NOT HAVE ACCESS
TO OUTSIDE MAKEUP AIR. YOU ARE ALWAYS USING INSIDE AIR. I'M IN FLORIDA
AND I DON'T WANT TO USE THE 90 DEGREE + AIR TO COOL DOWN TO 74.
--
Regards,

Tom Pryor
4188 Limerick Dr
Lake Wales, Fl 33859
Cell 248 470 9186

Living on a waterfront is not a matter of life or death. Its more
important than that.
 
Thank you ALL !!

and a special Thank You to Tom - nice work !!

I'll be investigating in the near future... and won't be surprised to discover some PO work in there.

All good,
Steve W
1973 23'
Southern California
 
> You may want to take a look at the modification that I employed in my 77 23B.
> Look at images as shown on: http://www.gmcmhphotos.com/photos/g7068-i-need-more-air.html
>
> My coach is still in the Barn, But I believe Karen Bradley has embraced the
> idea and plans to modify her Coach.

Just for the record, I have NOT installed this mod (though I started to).
Haven't decided whether to go this route, or the one where you mount the stock blower on the front of the box.
The advantage of that approach is you don't have a noisy blower in the cockpit with you, though it's
not quite as straight a path and you have to hack up the cover.

Sorry for being so slow to comment; I'm *way* behind on my forum reading as well as my GMC projects.
Just too darned busy!

Karen
1975 26'
 
> I suspect the Vintage Air system is the better way to go. I have the under dash plenum and unmodified it's weak. I have to dig in and make the
> modifications to help it as best I can, but I think the Vintage Air systems would be much more effective.

I second that: the 75/76 "max air vent", while an improvement, is nowhere near good enough by itself.
If you're going to the trouble, there are better solutions.

Karen
1975 26'
 
Interested to learn how the Bounds package is set up in the HVAC box. FAN-->C.COIL-->H..COIL-->VOLUME DAMPER?
--
Bill Van Vlack
'76 Royale; Guemes Island, Washington; Twin bed, full (DS) side bath, Brazilian Redwood counter and settee tops,455, 6KW generator; new owner a/o mid
November 2015.
 
Well... my old post / inquiry seems to have gotten some attention today.

Since then, I purchased an under dash air horn retrofit kit from Golby. It calls for some cutting...

Haven't started the project yet. It doesn't seem trivial. Will keep y'all posted.

As always -THANK YOU ALL for the wealth of help and information provided here.

SteveW
1973 23. Yellow
Southern California
 
If you drive in cool weather you can't vent fresh air in. Also if you get caught in a cold snap or at altitude in spring/fall your heat and def will
be 100% recirculated. If I had a pre 77 I would get the dash air working as designed then add a second evaporator either up ftont of furrher to the
rear of the coach. Even with a curtain cooling behind you should help up front.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I can’t speak for the efficiency of pre 77 coaches defog systems but I’ve
had 2 77’s and neither had any trouble keeping the windshield fog free even
in Seattle wet season. My first 77 did not even have any ducting other that
the center duct horn which was held in place on top of the metal under dash
only by gravity ( no instrument panel in that one). If you have an early
model heater box and windshield fogging issues take the system out of a
newer gen. Even old and dried up they work.

Sully
Who needs a pair of early toll window assemblies?
Bellevue.

On Wed, May 30, 2018 at 5:23 PM John R. Lebetski
wrote:

> If you drive in cool weather you can't vent fresh air in. Also if you get
> caught in a cold snap or at altitude in spring/fall your heat and def will
> be 100% recirculated. If I had a pre 77 I would get the dash air working
> as designed then add a second evaporator either up ftont of furrher to the
> rear of the coach. Even with a curtain cooling behind you should help up
> front.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
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