| Cock pit Fan Motor upgrade ? [message #287193] |
Sun, 13 September 2015 20:19  |
Tony Cook
Messages: 121
Registered: August 2014
Location: Torrance CA
Karma: 0
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Got the A/C system working with Dura Cool but the fan speed is just inadequate i know the cockpit kinda ' blows ' ! Has anyone put in a stronger fan or is there a upgrade. Thanks
Tony Cook
77' Kingsley ' SuperSession 77 '
Torrance Beach,CA
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #287197 is a reply to message #287193] |
Sun, 13 September 2015 20:38  |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Tony,
Change the blower motor. After 40+ years they have bearings that have dried out.
You want a Blower motor Part# PM102, under $25 most places. NAPA part# is a BK 6551039
AZ PM102
O’Reilly PM102
Change the motor first then make sure that the air box is changing for AC, Heater, Vent, Bilevel and Defrost.
JR Wright
GMC Great Laker MHC
GMC Eastern States Charter Member
GMCGL Tech Editor
GMCMHI
78 GMC Buskirk 30’ Stretch
1975 GMC Avion (Under Reconstruction)
Michigan
> On Sep 13, 2015, at 9:19 PM, Tony Cook wrote:
>
> Got the A/C system working with Dura Cool but the fan speed is just inadequate i know the cockpit kinda ' blows ' ! Has anyone put in a stronger fan
> or is there a upgrade. Thanks
> --
> Tony Cook
> 77' Kingsley ' SuperSession 77 '
> Torrance Beach,CA
>
> _______________________________________________
> GMCnet mailing list
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #287201 is a reply to message #287197] |
Sun, 13 September 2015 21:00 |
Tony Cook
Messages: 121
Registered: August 2014
Location: Torrance CA
Karma: 0
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Motor isn't binding or noisy but i hear ya even if a new motor added just a bit more oomf would be worth it. It will go through all speeds just doesnt seem like alot more when its in Max air mode
Tony Cook
77' Kingsley ' SuperSession 77 '
Torrance Beach,CA
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #287206 is a reply to message #287201] |
Sun, 13 September 2015 22:03 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Tony Cook wrote on Sun, 13 September 2015 19:00Motor isn't binding or noisy but i hear ya even if a new motor added just a bit more oomf would be worth it. It will go through all speeds just doesnt seem like alot more when its in Max air mode
I don't know much but seem to remember that there was some discussion about the air exchanger being clogged by varmints? Seems some creature set up housekeeping in the box. Not sure how they cleaned it.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #287215 is a reply to message #287206] |
Mon, 14 September 2015 00:41 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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The air distribution system is leaky at the seams and defaults to blowing mostly out the defrost passages when the inside doors lose their foam seals. I got a couple of used squirrel- cage mini blowers that were from computers and put them right behind the face vent registers. It's no blast in the face like some modern cars, but I didn't have to take the dash off and rebuild the entire distribution system. The fans are only $3 , and they operate on 12 volts. I got them from Electronic Goldmine: http://www.goldmine-elec-products.com/
http://www.goldmine-elec-products.com/prodinfo.asp?number=G19274
I think they have some larger ones too, but all they really do is help pull the conditioned air to the face vents and then throw it out so it doesn't all go out the leaks and the defroster vents.
If you get that new blower, make sure and check the rotation vs polarity, it will make quite a difference in the blower output when it is wired correctly.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Cock pit Fan Motor upgrade ? [message #287240 is a reply to message #287239] |
Mon, 14 September 2015 10:29 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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It was reported many moons ago that the squirrel cage assembly is unique to the GMC coach. So, apparently you can easily replace the motor, but the fan is another story.
You might also check that the water flow through the heater core is completely off. Installing a ball valve in the water line is the way to go.
Tom, MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Cock pit Fan Motor upgrade ? [message #287260 is a reply to message #287193] |
Mon, 14 September 2015 13:48 |
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SeanKidd
Messages: 747
Registered: June 2012
Location: Northern Neck Virginia
Karma: 4
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Don't forget, if you increase airflow too much, you may start carrying condensation through the evaporator and get unwanted humidity or water leak inside coach...there has to be a happy medium.
Sean and Stephanie
73 Ex-CanyonLands 26' #317 "Oliver"
Hubler 1-Ton, Quad-Bags, Rear Disc, Reaction Arms, P.Huber TBs, 3.70:1 LSD Honda 6500 inverter gen.
Colonial Travelers
[Updated on: Mon, 14 September 2015 13:48] Report message to a moderator |
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #288456 is a reply to message #287193] |
Sat, 10 October 2015 07:04 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Tim,
I'll assume you've downloaded Zay Brand's "Separating Hot..." booklet from
GMCWS.org and followed its excellent suggestions.
There have been several reports of debris between the evaporator and the
firewall. While it's difficult to remove the evaporator, you can easily
remove the resistor pack on the driver's side of the HVAC box. Using that
observation port you can check for blockage and even extract some with long
forceps and/or vacuum nozzles. An easy check that's worth the effort.
Ken H.
On Sun, Sep 13, 2015 at 9:19 PM, Tony Cook wrote:
> Got the A/C system working with Dura Cool but the fan speed is just
> inadequate i know the cockpit kinda ' blows ' ! Has anyone put in a
> stronger fan
> or is there a upgrade. Thanks
> --
>
_______________________________________________
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http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #288481 is a reply to message #288456] |
Sat, 10 October 2015 16:33 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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One of our faithful readers who doesn't like to post sent me some good
photos to illustrate my comments about evaporator clogging:
https://drive.google.com/folderview?id=0B3XquSIYjDleQndtYlp6SEtzbkE&usp=sharing
Ken H.
On Sat, Oct 10, 2015 at 8:04 AM, Ken Henderson
wrote:
> Tim,
>
> I'll assume you've downloaded Zay Brand's "Separating Hot..." booklet from
> GMCWS.org and followed its excellent suggestions.
>
> There have been several reports of debris between the evaporator and the
> firewall. While it's difficult to remove the evaporator, you can easily
> remove the resistor pack on the driver's side of the HVAC box. Using that
> observation port you can check for blockage and even extract some with long
> forceps and/or vacuum nozzles. An easy check that's worth the effort.
>
> Ken H.
>
>
> On Sun, Sep 13, 2015 at 9:19 PM, Tony Cook wrote:
>
>> Got the A/C system working with Dura Cool but the fan speed is just
>> inadequate i know the cockpit kinda ' blows ' ! Has anyone put in a
>> stronger fan
>> or is there a upgrade. Thanks
>> --
>>
>
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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: Cock pit Fan Motor upgrade ? [message #288486 is a reply to message #287193] |
Sat, 10 October 2015 19:32 |
Steve
Messages: 506
Registered: September 2013
Location: East Greenville, Pa
Karma: 1
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Senior Member |
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Great pictures Ken. I have to agree with Powerjon. I replaced the blower motor in my 78 and it made a big difference in air flow. Off the shelf from Auto zone.
1978 GMC Royal
Eastern Pennslyvania
1968 Chevrolet C20 396 Camper Special
1969 Chevrolet C20 Camper Special
1985 Buick Electra Park Avenue
1992 Camaro 25th Anniversary Heretage Edition Black
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| Re: [GMCnet] Cock pit Fan Motor upgrade ? [message #288668 is a reply to message #288550] |
Tue, 13 October 2015 17:26 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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JR,
IIRC the OEM dash air has something like 7 or 9 bends of 90° bends or more. Those bends create a massive pressure drop. If you
increase the flow the pressure drop increases and as you note "will not get you any more appreciative flow."
This is a hard concept for people to grasp, when Hamilton Standard worked with the Xian Aircraft Company to retrofit their Y-7 with
an air conditioning system we found lots of 90° bends in the ducting.
We ran the numbers to show them that by using two 45° bends the pressure drop would decrease and flow would increase greatly. They
still wanted us to sell them a bigger fan so we did. When it didn't work they got mad at us for selling it to them!
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: John Wright
The blower motor in good shape is more than sufficient to move air thru the AC system, speeding up the blower will not get you any
more appreciative flow because of all the restrictions within the early systems. The real problem is that the 1975 Type I AC system
was poorly designed and has poor air flow. The Type II design used in mostly 1976 and some very early 1977 coaches was actually
worse than the Type I system. The Type III system was the best of the designs that GM put in the coach and IMPO worked very well as
I sometimes needed to put a light blanket over my legs as it would get very cold.
Now there are a number of modifications that will allow the type I & II designs to flow more air. Some are the addition of an
another air path and some are more extensive in their scope.
http://www.gmcmhphotos.com/photos/g4122-ac-mod.html
http://www.gmcmhphotos.com/photos/g4463-hvac-removed.html
and
http://www.gmcmotorhome.com/tech/heatfan/index.html
http://www.gmceast.com/technical/Wall_HVAC_II_Systems.pdf
http://gmcws.org/Tech/air_conditioning/air_conditing.html
Pictures of process
http://www.gmcmhphotos.com/photos/g4637-type-ii-dash-air-condition-modification.html
You also can add an additional AC unit under the dash to augment or replace the AC portion of your dash HVAC unit. This is what I
have chosen to do on our 1975 GMC Avion Model. It will be in addition to modifications to increase air flow.
http://www.appliedgmc.com/prod.itml/icOid/849
The Factory A6 compressor is a monster and can operate several AC units. The Big Chevy Suburbans that came with the additional rear
AC units are an example. The newer Sanden units are pretty robust too.
http://www.appliedgmc.com/prod.itml/icOid/1658
or
http://www.appliedgmc.com/prod.itml/icOid/1423
And some have designed a whole new dash and AC unit using modern hardware. Bob Gummersal offered a complete parts list, pictures
and drawings to complete this modification, but I cannot find a link to that information. It should be noted here that this type of
modification is NOT for the unskilled personal.
JR
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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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