Roof Air Conditioner

9

930bob

Member
Feb 11, 2005
31
0
6
Hi All,
Has anyone had any issues with mounting the rear roof air conditioner backwards?
I will be replacing my rear unit with a low profile Carrier Unit and will have to mount
it backwards to get it to fit. My concerns are rain and wind entering the unit while driving.
Probably won't be necessary to operate it while driving but just wondering if anyone had any problems?
Thanks,
Bob Wheaton
--
'78 GMC Kingsley
NB,Canada
 
Bob,

That's the way John Sharpe mounted his rear Carrier and he doesn't have any problems with it.

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 bobwheaton
Sent: Tuesday, April 24, 2018 5:19 PM
To: gmclist
Subject: [GMCnet] Roof Air Conditioner

Hi All,
Has anyone had any issues with mounting the rear roof air conditioner backwards?
I will be replacing my rear unit with a low profile Carrier Unit and will have to mount
it backwards to get it to fit. My concerns are rain and wind entering the unit while driving.
Probably won't be necessary to operate it while driving but just wondering if anyone had any problems?
Thanks,
Bob Wheaton
--
'78 GMC Kingsley
NB,Canada
 
I mounted the rear A/C backward on my Avion. Needed to clear the rear clearance lights. Worked just fine while stationary on shore or generator power.
Never tried it while underway.
Tom
--
2012 Phoenix Cruiser model 2552
KA4CSG
 
I think the problem with the rear AC is the original duoTherm units were much shorter in length and had a different footprint.

Areodynamics and aesthetics aside, I think the only problem is having the condensor fins facing forward, they may tend to scoop up dust , debris and
bend fins.
--
76 Glenbrook
 
Many people have done this over the years and also run them going down the road with their Onan running.
I recall the Penguins were one of them that people mounted backwards.

Emery Stora

>
> I think the problem with the rear AC is the original duoTherm units were much shorter in length and had a different footprint.
>
> Areodynamics and aesthetics aside, I think the only problem is having the condensor fins facing forward, they may tend to scoop up dust , debris and
> bend fins.
> --
> 76 Glenbrook
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
I'm not sure about other air conditioners, but the Atwood Air Command
manual specifically states not to install them backwards:

"- The front of the unit MUST face the direction of travel; failure to
follow this instruction will result in damage to the condenser fans."

http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_DUCTED_02_05_2016_Rev_9.pdf

Eric
(no GMC, but my friend has one)

On Tue, Apr 24, 2018 at 3:19 PM, bobwheaton <

> Hi All,
> Has anyone had any issues with mounting the rear roof air conditioner
> backwards?
> I will be replacing my rear unit with a low profile Carrier Unit and will
> have to mount
> it backwards to get it to fit. My concerns are rain and wind entering the
> unit while driving.
> Probably won't be necessary to operate it while driving but just wondering
> if anyone had any problems?
> Thanks,
> Bob Wheaton
> --
> '78 GMC Kingsley
> NB,Canada
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Probably because the fans will spin backwards.

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 Eric Mears
Sent: Wednesday, April 25, 2018 10:32 AM
To: gmclist
Subject: Re: [GMCnet] Roof Air Conditioner

I'm not sure about other air conditioners, but the Atwood Air Command
manual specifically states not to install them backwards:

"- The front of the unit MUST face the direction of travel; failure to
follow this instruction will result in damage to the condenser fans."

http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_DUCTED_02_05_2016_Rev_9.pdf

Eric
(no GMC, but my friend has one)
 
The Fan can free wheel backwards when not in use, but minimal.

On Wed, Apr 25, 2018 at 9:17 AM, Rob Mueller
wrote:

> Probably because the fans will spin backwards.
>
> 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 Eric
> Mears
> Sent: Wednesday, April 25, 2018 10:32 AM
> To: gmclist
> Subject: Re: [GMCnet] Roof Air Conditioner
>
> I'm not sure about other air conditioners, but the Atwood Air Command
> manual specifically states not to install them backwards:
>
> "- The front of the unit MUST face the direction of travel; failure to
> follow this instruction will result in damage to the condenser fans."
>
> http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_
> DUCTED_02_05_2016_Rev_9.pdf
>
> Eric
> (no GMC, but my friend has one)
>
>
> _______________________________________________
> 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
 
I doubt the backwards freewheeling will be "minimal" at 60+ mph going down the freeway! :-)

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 Jim Kanomata
Sent: Wednesday, April 25, 2018 11:39 AM
To: gmclist
Subject: Re: [GMCnet] Roof Air Conditioner

The Fan can free wheel backwards when not in use, but minimal.

On Wed, Apr 25, 2018 at 9:17 AM, Rob Mueller
wrote:

> Probably because the fans will spin backwards.
>
> 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 Eric
> Mears
> Sent: Wednesday, April 25, 2018 10:32 AM
> To: gmclist
> Subject: Re: [GMCnet] Roof Air Conditioner
>
> I'm not sure about other air conditioners, but the Atwood Air Command
> manual specifically states not to install them backwards:
>
> "- The front of the unit MUST face the direction of travel; failure to
> follow this instruction will result in damage to the condenser fans."
>
> http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_
> DUCTED_02_05_2016_Rev_9.pdf
>
> Eric
> (no GMC, but my friend has one)
>
>
> _______________________________________________
> 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
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Is freewheeling the issue, or the fact that while running it in motion, the
incoming air pressure may slow or stop the fan?

On Wed, Apr 25, 2018 at 12:57 PM, Rob Mueller
wrote:

> I doubt the backwards freewheeling will be "minimal" at 60+ mph going down
> the freeway! :-)
>
> 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 Jim
> Kanomata
> Sent: Wednesday, April 25, 2018 11:39 AM
> To: gmclist
> Subject: Re: [GMCnet] Roof Air Conditioner
>
> The Fan can free wheel backwards when not in use, but minimal.
>
> On Wed, Apr 25, 2018 at 9:17 AM, Rob Mueller

>
> > Probably because the fans will spin backwards.
> >
> > 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 Eric
> > Mears
> > Sent: Wednesday, April 25, 2018 10:32 AM
> > To: gmclist
> > Subject: Re: [GMCnet] Roof Air Conditioner
> >
> > I'm not sure about other air conditioners, but the Atwood Air Command
> > manual specifically states not to install them backwards:
> >
> > "- The front of the unit MUST face the direction of travel; failure to
> > follow this instruction will result in damage to the condenser fans."
> >
> > http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_
> > DUCTED_02_05_2016_Rev_9.pdf
> >
> > Eric
> > (no GMC, but my friend has one)
> >
> >
> > _______________________________________________
> > 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
> _______________________________________________
> 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
>
 
I don't like the look of the backward mounting.
I used an Atwood commander 15000 heat pump in the mid and a brisk 13500 in the back.
--
1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
 
Probably both.

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 Will
Sent: Wednesday, April 25, 2018 12:02 PM
To: gmclist
Subject: Re: [GMCnet] Roof Air Conditioner

Is freewheeling the issue, or the fact that while running it in motion, the
incoming air pressure may slow or stop the fan?

On Wed, Apr 25, 2018 at 12:57 PM, Rob Mueller
wrote:

> I doubt the backwards freewheeling will be "minimal" at 60+ mph going down
> the freeway! :-)
>
> 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 Jim
> Kanomata
> Sent: Wednesday, April 25, 2018 11:39 AM
> To: gmclist
> Subject: Re: [GMCnet] Roof Air Conditioner
>
> The Fan can free wheel backwards when not in use, but minimal.
>
> On Wed, Apr 25, 2018 at 9:17 AM, Rob Mueller

>
> > Probably because the fans will spin backwards.
> >
> > 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 Eric
> > Mears
> > Sent: Wednesday, April 25, 2018 10:32 AM
> > To: gmclist
> > Subject: Re: [GMCnet] Roof Air Conditioner
> >
> > I'm not sure about other air conditioners, but the Atwood Air Command
> > manual specifically states not to install them backwards:
> >
> > "- The front of the unit MUST face the direction of travel; failure to
> > follow this instruction will result in damage to the condenser fans."
> >
> > http://www.atwoodmobile.com/manuals/ac/MPD_15078_AC_IOM_
> > DUCTED_02_05_2016_Rev_9.pdf
> >
> > Eric
> > (no GMC, but my friend has one)
> >
> >
> > _______________________________________________
> > 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
> _______________________________________________
> 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
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Blades that are curved to pull will be less effected by air coming at
opposit direction, plus the condenser fins are dense and there is enough
turbulense on the roof with other objects.

> I don't like the look of the backward mounting.
> I used an Atwood commander 15000 heat pump in the mid and a brisk 13500 in
> the back.
> --
> 1977 Kingsley 455 as stock as it gets except lots of Ragusa parts
>
> _______________________________________________
> 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
 
This has been a really interesting thread, and a lot of what has been written is accurate as far as I know. But, as a sailor of wind powered vessels
and a naval architect, I think that any problem with the ram air effect on the condenser fan could be erased but putting an obstruction in front of
the air intake buy no less than a fan diameter. That would end that.

Now all you need is a good ladder and a roof pod.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit
 
You must log in or register to reply here.
Get your shine on at www.cruzingear.co
GMCMI Spring 2026 Rally

Share this page

Share this page
Top Bottom
Back