WE ALL NEED MORE AIR

T

Tom Pryor

Member
Jan 9, 2011
162
4
18
Hi Folks. I just completed a modification to my HVAC box that can easily
copied by any and all.

It is generally known that the air flow in our OEM HVAC boxes are anemic at
best. The "why" in my opinion is the side mounted squirrel cage fan expels
air that must change directions twice before getting to cooling or heating
fins. It is generally agreed that the capacity of our A/C compressor and
system is sufficient. After reviewing the efforts of Ken Henderson and
others I wondered if there might be a way to modify the system without
removing the whole HVAC box to improve air flow and efficiency.

This modification is JWID:

1. It requires cutting an access hole in the floor of the coach to get
access to the Lower portion of the HVAC box, then cutting two square
holes in the box.

http://www.gmcmhphotos.com/
photos/i-need-more-air/p63444-thumb-img-0955-1024.html

2. I then Fashioned a Plenum to connect the floor to box.
http://www.gmcmhphotos.com/
photos/i-need-more-air/p63448-plenum-sketch.html
http://www.gmcmhphotos.com/
photos/i-need-more-air/p63449-thumb-img-0957-10241.html

3. A new floor insert was made and installed to accommodate a MCC
fan blower, PN 515 (
http://www.mcc-hvac.com/wp-content/uploads/2014/03/Blowers.pdf)

http://www.gmcmhphotos.com/photos/i-need-more-air/p63445-img-0967.html

http://www.gmcmhphotos.com/photos/i-need-more-air/p63447-img-0969.html

The OEM fan and fan and fan duct will be removed and filled with aluminum
plate. The Hi, Med, and Lo wiring will be transferred to the new Blower
fan. BTW this fan already has Hi, Med and Lo hook ups with appropriate
resistance devices built in. In addition, all the dash controls are not
molested and will function as original. I plan to have a nice teak
enclosure with filters to cover the ugliness of the fan.

Any and all comments are required!

--
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.
 
Hi Tom
It looks great. There are several blowers with PN515(. Could you please give the full model number? The information in the ( ) was cut off.

Emery Stora

>
> Hi Folks. I just completed a modification to my HVAC box that can easily
> copied by any and all.
>
> It is generally known that the air flow in our OEM HVAC boxes are anemic at
> best. The "why" in my opinion is the side mounted squirrel cage fan expels
> air that must change directions twice before getting to cooling or heating
> fins. It is generally agreed that the capacity of our A/C compressor and
> system is sufficient. After reviewing the efforts of Ken Henderson and
> others I wondered if there might be a way to modify the system without
> removing the whole HVAC box to improve air flow and efficiency.
>
> This modification is JWID:
>
> 1. It requires cutting an access hole in the floor of the coach to get
> access to the Lower portion of the HVAC box, then cutting two square
> holes in the box.
>
> http://www.gmcmhphotos.com/
> photos/i-need-more-air/p63444-thumb-img-0955-1024.html
>
> 2. I then Fashioned a Plenum to connect the floor to box.
> http://www.gmcmhphotos.com/
> photos/i-need-more-air/p63448-plenum-sketch.html
> http://www.gmcmhphotos.com/
> photos/i-need-more-air/p63449-thumb-img-0957-10241.html
>
> 3. A new floor insert was made and installed to accommodate a MCC
> fan blower, PN 515 (
> http://www.mcc-hvac.com/wp-content/uploads/2014/03/Blowers.pdf)
>
> http://www.gmcmhphotos.com/photos/i-need-more-air/p63445-img-0967.html
>
> http://www.gmcmhphotos.com/photos/i-need-more-air/p63447-img-0969.html
>
> The OEM fan and fan and fan duct will be removed and filled with aluminum
> plate. The Hi, Med, and Lo wiring will be transferred to the new Blower
> fan. BTW this fan already has Hi, Med and Lo hook ups with appropriate
> resistance devices built in. In addition, all the dash controls are not
> molested and will function as original. I plan to have a nice teak
> enclosure with filters to cover the ugliness of the fan.
>
> Any and all comments are required!
>
>
>
> --
> 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.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Sounds good, but after removing the OEM fan and duct work, what about the defrost function? I'm not worried about winter time use, but in the summer
the windshield can get condensation especially during a heavy rainstorm.

Pulling smooth (laminar) airflow through the coils will work much better than pushing turbulent air as in the OEM configuration.
--
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
Hubler 1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
 
My defroster was for chit anyway. I keep a towel on the instrument binnacle - it anchors the GPS too - and wipe as necessary.

--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've had a few requests concerning my post. The GMC Photo site is very
cumbersome and I have used only once. VERY DIFFICULT TO SEQUENCE IMAGES, EH!

IF YOU ALL GO TO
http://www.gmcmhphotos.com/photos/i-need-more-air/p63443-hvac-blower-modification.html.
IT IS THE TITLE PAGE. ALWAYS TOGGLE TO THE LEFT & YOU WILL GET THE FULL
MONTY!

ALSO: Emery Stora, wanted more Info on the fan assy. If you go to this
PDF file, it is located on page 226 model 515 with brushes and internal
resistors, eh.
http://www.mcc-hvac.com/wp-content/uploads/2014/03/Blowers.pdf
--
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.
 
Tom,

This is a great write-up! Thank you for posting it. What I haven't seen yet
is... how effective is it? Are you happy with the mod, and would you do
anything differently?

Thank you,

Guy Lopes
76 RB Birchaven
Sacramento, CA

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Thomas
Pryor
Sent: Monday, July 17, 2017 11:11 AM
To: gmclist
Subject: Re: [GMCnet] WE ALL NEED MORE AIR

I've had a few requests concerning my post. The GMC Photo site is very
cumbersome and I have used only once. VERY DIFFICULT TO SEQUENCE IMAGES, EH!
 
Thanks, Tom.
You might also want to post what model and year your GMC is. Different years had different venting of the air conditioner beneath the dash.

Emery Stora

>
> I've had a few requests concerning my post. The GMC Photo site is very
> cumbersome and I have used only once. VERY DIFFICULT TO SEQUENCE IMAGES, EH!
>
> IF YOU ALL GO TO
> http://www.gmcmhphotos.com/photos/i-need-more-air/p63443-hvac-blower-modification.html.
> IT IS THE TITLE PAGE. ALWAYS TOGGLE TO THE LEFT & YOU WILL GET THE FULL
> MONTY!
>
> ALSO: Emery Stora, wanted more Info on the fan assy. If you go to this
> PDF file, it is located on page 226 model 515 with brushes and internal
> resistors, eh.
> http://www.mcc-hvac.com/wp-content/uploads/2014/03/Blowers.pdf
> --
> 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.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
That squirrel cage is probably a lot quieter than the auxiliary cooler I have in the same spot.
--
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
 
While "Vintage Air" doesn't make a "GMC motorhome" specific HVAC system,
they did write me to let me know they could use universal components that
they have to make a modern AC system for the GMC. I'd imagine it wouldn't
be to difficult to get them to look into a GMC dash system if there was
enough interest.

Barring that, I am sure the "Jims" can offer parts to make the GMC dash AC
work better, too.

(more options the better)

Sammy

> That squirrel cage is probably a lot quieter than the auxiliary cooler I
> have in the same spot.
> --
> Bryan Hayes
> '76 Eleganza II
> Salt Lake City, Utah
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Sammy,
I bought the system from Jim K, actually I bought it from someone else who decided not to install it.

http://www.appliedgmc.com/prod.itml/icOid/849
or
http://www.appliedgmc.com/prod.itml/icOid/850

Works well with extensive rework and allows you to use the entire HVAC too.

JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan

>
> While "Vintage Air" doesn't make a "GMC motorhome" specific HVAC system,
> they did write me to let me know they could use universal components that
> they have to make a modern AC system for the GMC. I'd imagine it wouldn't
> be to difficult to get them to look into a GMC dash system if there was
> enough interest.
>
> Barring that, I am sure the "Jims" can offer parts to make the GMC dash AC
> work better, too.
>
> (more options the better)
>
> Sammy
>

>
>> That squirrel cage is probably a lot quieter than the auxiliary cooler I
>> have in the same spot.
>> --
>> Bryan Hayes
>> '76 Eleganza II
>> Salt Lake City, Utah
>>
>> _______________________________________________
>> 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
 
That should read “without extensive rework”

JR

>
> Sammy,
> I bought the system from Jim K, actually I bought it from someone else who decided not to install it.
>
> http://www.appliedgmc.com/prod.itml/icOid/849
> or
> http://www.appliedgmc.com/prod.itml/icOid/850
>
> Works well with extensive rework and allows you to use the entire HVAC too.
>
> JR Wright
> GMC Great Laker MHC
> GMC Eastern States Charter Member
> GMCGL Tech Editor
> GMCMI
> 78 GMC Buskirk 30’ Stretch
> 1975 GMC Avion (Under Reconstruction)
> Michigan
>
>

>>
>> While "Vintage Air" doesn't make a "GMC motorhome" specific HVAC system,
>> they did write me to let me know they could use universal components that
>> they have to make a modern AC system for the GMC. I'd imagine it wouldn't
>> be to difficult to get them to look into a GMC dash system if there was
>> enough interest.
>>
>> Barring that, I am sure the "Jims" can offer parts to make the GMC dash AC
>> work better, too.
>>
>> (more options the better)
>>
>> Sammy
>>

>>
>>> That squirrel cage is probably a lot quieter than the auxiliary cooler I
>>> have in the same spot.
>>> --
>>> Bryan Hayes
>>> '76 Eleganza II
>>> Salt Lake City, Utah
>>>
>>> _______________________________________________
>>> 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
 
Bryan,

The problem with the aux coolers is that they have small diameter squirrel cage blowers (3" or 3.5") and to move enough air they
have to spin rapidly creating a lot of noise, I have one in Double Trouble.

I found a unit on eBay that came out of a mid 1960's Ford Mustang which has 5 inch blowers. I have not installed it yet but I did
spin it up and it was MUCH quieter.

Here's a photo showing the blowers:

Tiny URL: http://tinyurl.com/yaf368mv

Full URL:

https://www.google.com.au/search?q=mustang+air+conditioning+units&rlz=1C1NHXL_enAU731AU731&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUK
Ewjpx5HHwJHVAhUDHZQKHZMoC-UQsAQIQQ&biw=1280&bih=591=N5F60NKHvDEi9M:

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] On Behalf Of Bryan Hayes
Sent: Tuesday, July 18, 2017 5:46 AM
To: gmclist
Subject: Re: [GMCnet] WE ALL NEED MORE AIR

That squirrel cage is probably a lot quieter than the auxiliary cooler I have in the same spot.
--
Bryan Hayes
 
Yes the squirrel cage will be quiet as it is drawing the inside air into
the system, BUT the air coming out of the registers will be noisy as your
uni, as there is turbulence coming through the ducts and grill.

> That squirrel cage is probably a lot quieter than the auxiliary cooler I
> have in the same spot.
> --
> Bryan Hayes
> '76 Eleganza II
> Salt Lake City, Utah
>
> _______________________________________________
> 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
 
Thomas,
This seems like a pretty straight forward modification to solve the (my) '76 non-recirc HVAC box issues if it will work with those boxes. Certainly
less of a mish-mash than other solutions. From the Jay Brand 'hot and cold' document, it seems like it might. Anxious to see how it performs in
service.
--
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; Since arrival: New HVAC blower, heat flap cable, headlight switch.
 
After reviewing the available schematics of 73 Thru 78 all versions
supplymake-up air to the same location.
They all pressurize the box from a single squirrel cage fan located on the
side of the box.

MAKE UP AIR and VENTING were some of the major changes in 77/78, along with
other non- air related improvements. . Neither of these would be
impediments to this modification, IMHO.

The Modification that I am suggesting:

1. Pressurizes the box with makeup air from only one
source.........INSIDE RECIRCULATING AIR.

2. The air direction now enters thru the front of the box, in the most
advantageous direction. Air entering the OEM design has at least two
restrictions BEFORE reaching the A/C or heater coil. This MOD significantly
remedies that flaw.

3. The journey requires easily accessible items: A) Block off all
unused external HVAC box passages, B) make and install the necessary
duct work, C) hook up HI, MED & LOW from old wires Resister wires to the
new resistor pack on the MCC 515 fan/motor assy.
4. Nothing in the Dash control assembly requires any attention.

5. For those who have the a pre 77/78 with no Recirculation feature,
this becomes a major improvement.

HOW CAN I HELP?-

--
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.
 
Tom
The reason I asked what year you had modified was because my 1977 and most 1977 and all 1978s have a heat duct at the floor right in the center of the motorhome.
This appears to be right where you mount the blower motor. Does this still allow the 77-78 models to have the floor heat duct there?

Emery Stora
77 Kingsley
Frederick, CO

>
> After reviewing the available schematics of 73 Thru 78 all versions
> supplymake-up air to the same location.
> They all pressurize the box from a single squirrel cage fan located on the
> side of the box.
>
> MAKE UP AIR and VENTING were some of the major changes in 77/78, along with
> other non- air related improvements. . Neither of these would be
> impediments to this modification, IMHO.
>
> The Modification that I am suggesting:
>
> 1. Pressurizes the box with makeup air from only one
> source.........INSIDE RECIRCULATING AIR.
>
>
> 2. The air direction now enters thru the front of the box, in the most
> advantageous direction. Air entering the OEM design has at least two
> restrictions BEFORE reaching the A/C or heater coil. This MOD significantly
> remedies that flaw.
>
> 3. The journey requires easily accessible items: A) Block off all
> unused external HVAC box passages, B) make and install the necessary
> duct work, C) hook up HI, MED & LOW from old wires Resister wires to the
> new resistor pack on the MCC 515 fan/motor assy.
> 4. Nothing in the Dash control assembly requires any attention.
>
> 5. For those who have the a pre 77/78 with no Recirculation feature,
> this becomes a major improvement.
>
> HOW CAN I HELP?-
>
>
> --
> 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.
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
"The reason I asked what year you had modified was because my 1977 and most
1977 and all 1978s have a heat duct at the floor right in the center of the
motorhome.
This appears to be right where you mount the blower motor. Does this still
allow the 77-78 models to have the floor heat duct there?"

My coach is a 77 Birchaven. The floor duct is about 6" above the double
squirrel relocated fan. That said, a deflector attached to the passenger
side instrument panel directs air flow to passenger and driver location.
(Side Car) That deflector also prevents air flow to the area between the
seats where there are no occupants. Just say'n.

I PUT THIS DWG UP ON THE PHOTO SITE. HOPE IT HELPS
http://www.gmcmhphotos.com/photos/i-need-more-air/p63460-h-hvac-flow.html

--
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.
 
Hey Tom,
Where did you buy the blower? I'm not having much luck finding it online.

thanks,
Karen
1975 26'

> I've had a few requests concerning my post. The GMC Photo site is very
> cumbersome and I have used only once. VERY DIFFICULT TO SEQUENCE IMAGES, EH!
>
> IF YOU ALL GO TO
> http://www.gmcmhphotos.com/photos/i-need-more-air/p63443-hvac-blower-modification.html.
> IT IS THE TITLE PAGE. ALWAYS TOGGLE TO THE LEFT & YOU WILL GET THE FULL
> MONTY!
>
> ALSO: Emery Stora, wanted more Info on the fan assy. If you go to this
> PDF file, it is located on page 226 model 515 with brushes and internal
> resistors, eh.
> http://www.mcc-hvac.com/wp-content/uploads/2014/03/Blowers.pdf
 
I did some searching

There are similar blowers on amazon:

https://www.amazon.com/gp/aw/d/B06XX9YLY1/ref=mp_s_a_1_22?ie=UTF8&qid=1501555275&sr=8-22&pi=AC_SX236_SY340_QL65&keywords=bus+blower+fan&dpPl=1&dpID=413y8OpY5YL&ref=plSrch

Maybe chinese knock off??? I do not know.

Down the road from me is a business that sells buses. They also sell truck accessories, and they are a dealer of the fan tom has listed. I have
not called and checked price and availability yet. Our local freightliner dealer is listed as well.
--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/
 
I found some on ebay as well, but they seldom list the specs. The ones Tom found seem
to have pretty good CFM numbers, plus the three speed resistor pack we need (I think).
I've seen a bunch that have much lower CFM ratings.

> I did some searching
>
> There are similar blowers on amazon:

thanks,
Karen
1975 26'
 
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