| dash Ac add-on [message #255260] |
Sun, 13 July 2014 19:22  |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Good evening, I thought occurred to me about the dash AC's in the TZE beasties. Has anyone ever attempted or been able to take the rear AC unit from say a suburban and put it under a dinette seat and plumb it in and make a duct system in the area behind the driver to cool the driver from behind and keep the passengers comfy also. I realize there is some work involved with AC lines and valving and controls but thats just textbook and would just have to be done.I have tried running the roof air but it has a hard time making it to the driver area and doesn't do much for the passengers either. My understanding is the onan runs cheaper than running the dash air, so I would much rather run it, and it runs very good. I guessing the dash air pulls about 2-3 mpg by the way it lugs down the motor and the onan only burns about 1/2 gallon an hour. Also haven't really paid much attention but when you have dual roof airs is the front normally in the front or center hole. Seems as if it was in the front roof hole it would do a better job on cooling the cockpit and alot quieter while sleeping in the rear. I know I seemed to ramble around on thoughts but that's the way it came out of my fingers. Any ideals, thoughts or facts known on the above would be welcome.
Skip Hartline
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: dash Ac add-on [message #255271 is a reply to message #255260] |
Sun, 13 July 2014 20:39  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
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If two roof airs they were center and rear. When I replaced my two I made them front and rear and installed a Maxxair vent in the center. There have been some who have installed aux AC units from the rear of vans or SUVs. A search of the photo archive may turn something up.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
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| Re: dash Ac add-on [message #255287 is a reply to message #255279] |
Sun, 13 July 2014 22:18 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Skip,
If you use the engine driven compressor to supply your add-on unit, you will still be losing that power and gas mileage.
My rooftop A/C blows enough air to fog the windshield if I'm not rolling, even when I've got the airflow divided between front and rear and the fan on low. And it gives me a cool uncomfortable chill on the back of my neck when I'm up front but does not blow any air on my face, which is where I want it. The dash A/C is practically useless in terms of airflow, so I am making the Onan functional to operate that roof air while underway through the hot zones in the U.S.. Mine is the old Mark IV unit and I used a K&N filter element in instead of the range vent type that was in there. Does your rooftop unit not put out enough airflow? Mine is located right at the doorway, is yours located in the same place?
Maybe you could attach some flat ducting to the roof air unit (like you can find in some of the modern vehicles) and get the airflow to the places you want. That way you would save the power and gas mileage like you said.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] dash Ac add-on [message #255292 is a reply to message #255283] |
Sun, 13 July 2014 22:26 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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You're right about the basic system being able to support an additional
evaporator, but your estimate of A-6 capacity is 'way low: It's actually
42,000 BTU at 4000 rpm. Even the little Sanden-style compressors are rated
above 30,000 BTU.
Here's a good reference:
http://www.heco.net/MainCat/Compressors.pdf
Ken H.
On Sun, Jul 13, 2014 at 10:40 PM, A. wrote:
> ...
>
>
The OEM compressor and condenser have ample
> excess capacity to handle a second evaporator. The A6 compressor is
> capable of servicing a system that can remove about 13,000 BTUs of heat per
> hour,
> about the same as a roof unit. The limiting factor in the factory dash
> air is the airflow over the evaporator and to/from the passenger
> compartment.
> You are on the right track considering a second evaporator.
> ...
>
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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] dash Ac add-on [message #255299 is a reply to message #255287] |
Sun, 13 July 2014 23:25 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Terry,
Lots of people run the front roof air going down the road, that's nothing new.
Running the Onan is going to effect mileage as well and there is no way I would try and guess which one would consume more as I'd be
pulling the answer right out of where the sun never shines!
Regards,
Rob M.
The Pedantic Mechanic
USAussie - Downunder
USA '75 Avion - Double Trouble TZE365V100426
AUS '75 Avion - The Blue Streak TZE365V100428
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org [mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Terry
Skip,
If you use the engine driven compressor to supply your add-on unit, you will still be losing that power and gas mileage.
My rooftop A/C blows enough air to fog the windshield if I'm not rolling, even when I've got the airflow divided between front and
rear and the fan on low. And it gives me a cool uncomfortable chill on the back of my neck when I'm up front but does not blow any
air on my face, which is where I want it. The dash A/C is practically useless in terms of airflow, so I am making the Onan
functional to operate that roof air while underway through the hot zones in the U.S.. Mine is the old Mark IV unit and I used a K&N
filter element in instead of the range vent type that was in there. Does your rooftop unit not put out enough airflow? Mine is
located right at the doorway, is yours located in the same place?
Maybe you could attach some flat ducting to the roof air unit (like you can find in some of the modern vehicles) and get the airflow
to the places you want. That way you would save the power and gas mileage like you said.
--
Terry
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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] dash Ac add-on [message #255303 is a reply to message #255299] |
Mon, 14 July 2014 00:28 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Roger that Rob!
I was just going by what Skip said, but I didn't try to do exact math on it. With my cruiser gearing in the final and an old transmission pulling a minivan towd, I'll probably need all the power I can get out of the 455. Besides that, I can get more airflow from where the sun don't shine than what comes outta the dash A/C vents! And I didn't think the roof A/C used a rotary compressor, but I did know about the triple energy conversions being less efficient than being driven right off the engine. If only the dash A/C worked as well as any of the units in any of the cars I've ever owned. And it seems like that is the case in a lot of RVs that I've worked on.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: dash Ac add-on [message #255309 is a reply to message #255260] |
Mon, 14 July 2014 06:25 |
skip2
Messages: 544
Registered: September 2011
Location: Winter Haven,FL (center o...
Karma: 3
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Senior Member |
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I came up with 2-3 mpg loss with AC use from my suburban and my work 2012 GMC Sierra which both I says they drop about 2-3 mpg when the AC kicks on. So if we did simple math of 10 mpg at 60 mph that would be 6 gallons per hour if we got 8 mpg that would be 7.5 gallons per hour. Yes my forward roof AC is at the doorway, been wanting to redo the headliner, sounds like a good time to come up with a forward duct work. The only time you really feel the roof air when going down the road is when you stop quickly and it's like the cold air keeps moving forward since it is heavier.
Skip Hartline
74 Canyon Lands, FiTech,
3.7 FD LSD, Manny Tranny,
Springfield Distributor,
2001 Chevy Tracker Ragtop Towd
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| Re: dash Ac add-on [message #255372 is a reply to message #255260] |
Mon, 14 July 2014 18:48 |
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SteveW
Messages: 538
Registered: June 2005
Location: Southern California - Ora...
Karma: 1
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Senior Member |
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Thanks Randy -
That Nostalgic under dash unit looks pretty appealing...
I was planning on fabricating a small table to "clip" onto the dash - with cup holders and the like.
Perhaps this unit could be installed and configured such that it doubles as a small tabletop and aux A/C. Nice !!
Gonna do some measuring...
Steve W
Southern California
1973 23'
Steve W
1973 : 23'
Southern California
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