A.C. Compressor (trivia)

T

travis martin

New member
Jan 18, 1999
267
2
0
Okay, since all we are having to locate is the evaporator and its fan, how
about the space above the refrigerator? For that matter, I don't suppose
there's any limit to how many evaporators one could install other than the
practical considerations. Possibly two small evaporators instead of one
larger one? The Frigidaire units, complete with blowers, that are factory
installed on practically every Suburban down here are small...about six
inches tall, eighteen wide and twelve deep, including the blower, and come
with an expansion valve installed...all we would have to worry about would
be refrigerant piping and building a suitable enclosure and ductwork.

Travis

- -----Original Message-----
From: Gcbr
To: gmcmotorhome
Date: Thursday, April 22, 1999 11:07 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>Travis
>
>No reason to not chase this. It will take some work. Now as to the location
>of the other evaporator. You want the intake as high as you can get it.
>Hot air rises like the balloons do. It will stay trapped there unless of
suck
>it down to the evaporator. One thing good I can say good about my SOB
>is that the AC air intake is in the ceiling--------keeps the beast real
cool.
>Hottest air is taken into the evap and spit out on high. Good design.
>
>Take Care
>Arch
>
>In a message dated 4/22/99 10:45:24 PM Central Daylight Time,

>
>>
>> The principle is sound. Shouldn't take a lot of design work to make
>> practical. Now wouldnt this be a dream? A GMC coach with a slick top, no
>> noise from the roof ac units...cold air from the dash registers and from
a
>> concealed unit, say about where the oven is now. A 5HP hermetic
compressor
>> under the hood out of the way. Under way, the engine powers it. Parked,
>> shore power or genset runs the hermetic. Sounds sweet to me. Any reason
not
>> to pursue this?
>>
>
>
 
Don't know why it bounced...that's the right address. ISP may have had a
problem. Please try again

Travis

- -----Original Message-----
From: Billy Massey
To: gmcmotorhome
Date: Thursday, April 22, 1999 11:38 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>Travis, what's your email addy? I sent you a note at travism and
>it bounced back to me.
>

>
>
>bdub
>'76 Palm Beach
>In The Heart o Texas
>www.web-access.net/~bmassey/
>icq # 202333
>
 
I like it! This solves the oil control issue that Mark referred to; only one
compressor with dual power sources. The electric motor can simply
"freewheel" when the compressor is powered off of the engine, and the clutch
is open when powered by the electric motor.

If we keep it up, we just might come up with a good idea. Can you elaborate
a bit on the bus AC that you mention? I'd like to know how the did it.

Travis

- -----Original Message-----
From: Donald W. Miller
To: gmcmotorhome
Date: Friday, April 23, 1999 12:06 AM
Subject: Re: GMC: A.C. Compressor (trivia)

>
>Hi Travis,
>
>I have been working toward your dream A/C system with an added twist.
>
>The A-6 is good for 36,000 btu conservative, but I found a bus A/C unit
>rated 50,000 btu using our same old A-6 compressor.
>
>Last summer I replaced both rooftop A/C units with vents, Max covers and
>fans. My vents stayed open all summer and there were no problems with
water
>entry. We had some thunderstorms with high winds so there were several
good
>tests. It stayed surprisingly cool inside most days.
>
>My system will use the A-6 as my sole compressor.
>
>On shorepower I will power it with a 2 hp 120 volt dual capacitor motor.
>Plans are to add a 2nd V belt sheave on a shaft extension screwed into the
>1/2" pipe threads on the front of the A-6 shaft.
>
>I think this will be workable, if not my backup with shorepower is a 120
>volt compressor from a window A/C with check valves in the high pressure
>lines. (Similar to what you mention)
>
>I plan to use a second similar size condenser to supply my rear evaporator.
>Together these two condensers have more capacity than any large single unit
>I could find.
>
>An inexpensive common 120v box fan in front of the condensers will cool
them
>when on shorepower.
>
>Hopefully I'll get the entire project finished this summer. I'm hanging on
>to my rooftop units in case there is an oversight and I have to back out of
>my A/C modifications.
>
>Don Miller (in the experimental mode)
>75 Glennbrook project
>Shenandoah Valley of Virginia
>
>
>
>Travis said:
>
>> I have dreamed of building an "integrated" system that would use one
large
>> condenser, the dash evaporator and a rear evaporator, and two
>> compressors...the A-6 that is engine mounted and parallel it with a
>hermetic
>> electric. Each compressor's check valves would keep it from being a
>problem
>> when the other was running. You'd have to have a large electric fan to
>cool
>> the condenser when running on 120 volts. But this would get rid of the
>need
>> for the noisy protruberances on the roof.
>>
>> Perhaps the condenser for this arrangement could be somewhere besides in
>> front of the radiator, though I don't see why the present location
>wouldn't
>> be just fine.
>>
>> Any thoughts on this?
>>
>> Travis
>
>
>
>
 
Research R-12...is this anything like medicinal whiskey?

Travis

- -----Original Message-----
From: Mark Grady
To: gmcmotorhome
Date: Friday, April 23, 1999 12:16 AM
Subject: RE: GMC: A.C. Compressor (trivia)

>Travis & Arch --
>
>Solid ideas, cool! (pun intended) That would make the
Suburban/Astro/Savanna
>rear A/C unit seem to be the logical choice, since you could mount it in
the
>ceiling close to where the rear Duo-therm is now. You'd have to plumb it of
>course, perhaps with nylon barrier hose. You'd also have to drain the
>condensate, easy to do.
>
>I haven't looked at the design of one of these recently but I doubt they've
>changed much. I'm getting junk yard fever. Now if we get a day it doesn't
>rain...
>
>Now, I gotta' see how to convert my 6K Onan to 220 to run a 3ton sealed
>compressor... and see how my supply of pure grade 'research' R-12 is
holding
>out.
>
>Mark
>
>> -----Original Message-----
>> From: owner-gmcmotorhome
>> [mailto:owner-gmcmotorhome]On Behalf Of Gcbr
>> Sent: Thursday, April 22, 1999 11:01 PM
>> To: gmcmotorhome
>> Subject: Re: GMC: A.C. Compressor (trivia)
>>
>>
>> Travis
>>
>> No reason to not chase this. It will take some work. Now as to
>> the location
>> of the other evaporator. You want the intake as high as you can get it.
>> Hot air rises like the balloons do. It will stay trapped there
>> unless of suck
>> it down to the evaporator. One thing good I can say good about my SOB
>> is that the AC air intake is in the ceiling--------keeps the
>> beast real cool.
>> Hottest air is taken into the evap and spit out on high. Good design.
>>
>> Take Care
>> Arch
>>
>> In a message dated 4/22/99 10:45:24 PM Central Daylight Time,

>>
>> >
>> > The principle is sound. Shouldn't take a lot of design work to make
>> > practical. Now wouldnt this be a dream? A GMC coach with a
>> slick top, no
>> > noise from the roof ac units...cold air from the dash
>> registers and from a
>> > concealed unit, say about where the oven is now. A 5HP
>> hermetic compressor
>> > under the hood out of the way. Under way, the engine powers it.
Parked,
>> > shore power or genset runs the hermetic. Sounds sweet to me.
>> Any reason not
>> > to pursue this?
>> >
>>
>
>
 
That's going to depend on the yard. Around here, I know of a couple that are
fairly reasonable, and since virtually every suburban sold around here for
the last 20 years came with one and they rarely fail, should be a high
supply/low demand item. I'll see what they can be had for. (Hope Winston
Churchill isn't monitoring...he'll chide me for ending that sentence with a
preposition...)

Travis

- -----Original Message-----
From: Mark Grady
To: gmcmotorhome
Date: Friday, April 23, 1999 7:42 AM
Subject: RE: GMC: A.C. Compressor (trivia)

>I'd say this is one very good solution. I used the area above me
>refrigerator as a convection cool 'channel' for the refrigerator (I'm still
>using the original 12v only model).
>
>That would be close to the center Duo-therm location though, add one in the
>back and you're in pretty good shape.
>
>Now, how much do you suppose these cost at the salvage yard?
>
>Mark
>
>> -----Original Message-----
>> From: owner-gmcmotorhome
>> [mailto:owner-gmcmotorhome]On Behalf Of Travis Martin
>> Sent: Thursday, April 22, 1999 7:01 AM
>> To: gmcmotorhome
>> Subject: Re: GMC: A.C. Compressor (trivia)
>>
>>
>> Okay, since all we are having to locate is the evaporator and its fan,
how
>> about the space above the refrigerator? For that matter, I don't suppose
>> there's any limit to how many evaporators one could install other than
the
>> practical considerations. Possibly two small evaporators instead of one
>> larger one? The Frigidaire units, complete with blowers, that are factory
>> installed on practically every Suburban down here are small...about six
>> inches tall, eighteen wide and twelve deep, including the blower, and
come
>> with an expansion valve installed...all we would have to worry about
would
>> be refrigerant piping and building a suitable enclosure and ductwork.
>>
>> Travis
>>
>> -----Original Message-----
>> From: Gcbr
>> To: gmcmotorhome
>> Date: Thursday, April 22, 1999 11:07 PM
>> Subject: Re: GMC: A.C. Compressor (trivia)
>>
>>
>> >Travis
>> >
>> >No reason to not chase this. It will take some work. Now as to
>> the location
>> >of the other evaporator. You want the intake as high as you can get it.
>> >Hot air rises like the balloons do. It will stay trapped there unless of
>> suck
>> >it down to the evaporator. One thing good I can say good about my SOB
>> >is that the AC air intake is in the ceiling--------keeps the beast real
>> cool.
>> >Hottest air is taken into the evap and spit out on high. Good design.
>> >
>> >Take Care
>> >Arch
>> >
>> >In a message dated 4/22/99 10:45:24 PM Central Daylight Time,

>> >
>> >>
>> >> The principle is sound. Shouldn't take a lot of design work to make
>> >> practical. Now wouldnt this be a dream? A GMC coach with a
>> slick top, no
>> >> noise from the roof ac units...cold air from the dash
>> registers and from
>> a
>> >> concealed unit, say about where the oven is now. A 5HP hermetic
>> compressor
>> >> under the hood out of the way. Under way, the engine powers
>> it. Parked,
>> >> shore power or genset runs the hermetic. Sounds sweet to me.
>> Any reason
>> not
>> >> to pursue this?
>> >>
>> >
>> >
>>
>
>
 
Travis --

Me too! Me too!

The A-6 was originally used as far back as '59. Almost always black, green
ones are reverse rotation used in the Corvair and some industrial
applications. The A6 produces 12 cubic inches per rotation. Through about
'76 (varies by model year) these compressors were installed to run
constantly, and used a suction throttling valve (STV) or POA valve to
regulate the evaporator pressure and prevent freeze up.

The R-4 produces 10 cubic inches per rotation, and has been replaced with
the DA-6 starting in 1985. It produces 9 cubes.

These are not as reliable (IMHO) as the Sanden/Sankyo designed in Texas but
built in Japan. It was originally the Abacus model. Model 508 is 5 cylinders
and 8 cu in; 505 is well, you got it, 5 cyl and 5 cu in. Very smooth,
running, with a larger clutch for cycling controlled orifice tube (CCOT)
applications.

Side note: early Chryslers used a V-2, almost all early Fords used a
Tecumseh or York (looks like a lawn mower engine.) These were all 6 to 10 cu
in. Later Fords use the Nippondenso, so do some Chryslers, they are 9 cu in.

FWIW, the downside of the A6 is its enormous capacity. Modern efficient
refrigeration designs call for a larger condenser and smaller, more
efficient compressor. That isn't the A6. It came to life at time when it ran
continuously, and head pressure was limited by modulating the suction line.
Our GMC's use a cycling clutch, where a thermostat turns the compressor off
as the evaporator approaches the freezing point. The condenser on our GMCs
are large, which keeps head pressure manageable.

I worked on many full sized GM cars that frequently had problems due to
smallish condensers (by design) and would tend to pop off refrigerant when
the fan clutches got 'lazy'. Further, by having the evaporator flooded with
liquid refrigerant, evap cores frequently 'rotted' out from the inside out.
This was because super heated R-12 would reduce the receiver dryer's ability
to keep even the smallest amount of moisture out of the system and held in
the desiccant. The resulting acid ate through aluminum evaporators like a
knife through butter.

End of the history lesson.

Mark

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Travis Martin
> Sent: Thursday, April 22, 1999 8:29 PM
> To: gmcmotorhome
> Subject: Re: GMC: A.C. Compresser
>
>
> Finally I get to contribute something useful.
>
> "A-6" Stands for Axial 6 cylinder. This compressor has 6
> cylinders arranged
> axially. It is extremely efficient and reliable. If you ever tear one down
> or look at an exploded drawing you will understand why my had is
> off to the
> designer. There oughta be a museum for such elegant designs. And
> yes it will
> accept the "modern" refrigerants just fine, though you will need to change
> to compatible oil.
>
> It was replaced starting in the mid 70's on smaller GM cars and
> gradually on
> just about everything by a compressor designated "R-4" which
> meant Radial 4
> cylinder. Because it is a radial design...kinda like a Pratt&Whitney
> airplane engine...it is shorter but somewhat larger in diameter.
> Both are of
> nearly the same displacement. The early R-4's were somewhat unreliable but
> later units seem to be holding up well.
>
>
 
Bravo!

Mark, this is the kind of post that keeps me looking forward to reading my
email every day. It is a poor day that I can't learn something. Some of that
I knew...like the STV/POA...but a heckuva bunch I didn't...like the reverse
rotation A-6. I didn't realize there was such a thing or that a Corvair
would use it. I guess the only difference would be the oil pump...the swash
plate and pistons wouldn't care which way they were turned.

Since you obviously DO know your butt from the North Star, perhaps you could
volunteer an opinion on how big an evaporator the A-6 and stock condenser
could support to cool the rear while underway?

I have dreamed of building an "integrated" system that would use one large
condenser, the dash evaporator and a rear evaporator, and two
compressors...the A-6 that is engine mounted and parallel it with a hermetic
electric. Each compressor's check valves would keep it from being a problem
when the other was running. You'd have to have a large electric fan to cool
the condenser when running on 120 volts. But this would get rid of the need
for the noisy protruberances on the roof.

Perhaps the condenser for this arrangement could be somewhere besides in
front of the radiator, though I don't see why the present location wouldn't
be just fine.

Any thoughts on this?

Travis

- -----Original Message-----
From: Mark Grady
To: gmcmotorhome
Date: Thursday, April 22, 1999 9:30 PM
Subject: RE: GMC: A.C. Compressor (trivia)

>Travis --
>
>Me too! Me too!
>
>The A-6 was originally used as far back as '59. Almost always black, green
>ones are reverse rotation used in the Corvair and some industrial
>applications. The A6 produces 12 cubic inches per rotation. Through about
>'76 (varies by model year) these compressors were installed to run
>constantly, and used a suction throttling valve (STV) or POA valve to
>regulate the evaporator pressure and prevent freeze up.
>
>The R-4 produces 10 cubic inches per rotation, and has been replaced with
>the DA-6 starting in 1985. It produces 9 cubes.
>
>These are not as reliable (IMHO) as the Sanden/Sankyo designed in Texas but
>built in Japan. It was originally the Abacus model. Model 508 is 5
cylinders
>and 8 cu in; 505 is well, you got it, 5 cyl and 5 cu in. Very smooth,
>running, with a larger clutch for cycling controlled orifice tube (CCOT)
>applications.
>
>Side note: early Chryslers used a V-2, almost all early Fords used a
>Tecumseh or York (looks like a lawn mower engine.) These were all 6 to 10
cu
>in. Later Fords use the Nippondenso, so do some Chryslers, they are 9 cu
in.
>
>FWIW, the downside of the A6 is its enormous capacity. Modern efficient
>refrigeration designs call for a larger condenser and smaller, more
>efficient compressor. That isn't the A6. It came to life at time when it
ran
>continuously, and head pressure was limited by modulating the suction line.
>Our GMC's use a cycling clutch, where a thermostat turns the compressor off
>as the evaporator approaches the freezing point. The condenser on our GMCs
>are large, which keeps head pressure manageable.
>
>I worked on many full sized GM cars that frequently had problems due to
>smallish condensers (by design) and would tend to pop off refrigerant when
>the fan clutches got 'lazy'. Further, by having the evaporator flooded with
>liquid refrigerant, evap cores frequently 'rotted' out from the inside out.
>This was because super heated R-12 would reduce the receiver dryer's
ability
>to keep even the smallest amount of moisture out of the system and held in
>the desiccant. The resulting acid ate through aluminum evaporators like a
>knife through butter.
>
>End of the history lesson.
>
>Mark
>
>
>
>> -----Original Message-----
>> From: owner-gmcmotorhome
>> [mailto:owner-gmcmotorhome]On Behalf Of Travis Martin
>> Sent: Thursday, April 22, 1999 8:29 PM
>> To: gmcmotorhome
>> Subject: Re: GMC: A.C. Compresser
>>
>>
>> Finally I get to contribute something useful.
>>
>> "A-6" Stands for Axial 6 cylinder. This compressor has 6
>> cylinders arranged
>> axially. It is extremely efficient and reliable. If you ever tear one
down
>> or look at an exploded drawing you will understand why my had is
>> off to the
>> designer. There oughta be a museum for such elegant designs. And
>> yes it will
>> accept the "modern" refrigerants just fine, though you will need to
change
>> to compatible oil.
>>
>> It was replaced starting in the mid 70's on smaller GM cars and
>> gradually on
>> just about everything by a compressor designated "R-4" which
>> meant Radial 4
>> cylinder. Because it is a radial design...kinda like a Pratt&Whitney
>> airplane engine...it is shorter but somewhat larger in diameter.
>> Both are of
>> nearly the same displacement. The early R-4's were somewhat unreliable
but
>> later units seem to be holding up well.
>>
>>
>
 
Arch, thanks for the note. I didn't realize that this was common practice on
boats. Not many boats around here, and none that I know of with AC...

Dual evaporators, on the other hand, are extremely common. Almost all
Suburbans and vans have rear evaporators. And the Suburban is the National
Car of Texas.

The principle is sound. Shouldn't take a lot of design work to make
practical. Now wouldnt this be a dream? A GMC coach with a slick top, no
noise from the roof ac units...cold air from the dash registers and from a
concealed unit, say about where the oven is now. A 5HP hermetic compressor
under the hood out of the way. Under way, the engine powers it. Parked,
shore power or genset runs the hermetic. Sounds sweet to me. Any reason not
to pursue this?

Travis
- -----Original Message-----
From: Gcbr
To: gmcmotorhome
Date: Thursday, April 22, 1999 10:12 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>Travis
>
>I have some good theory for you. Fact there have been more than one unit
>built with more than one evaporator. Theory at 12 cb.in. you should be able
>to get close to 60,000 btus out of it (dont have books in front of me).
>The 2 compressor arrangement is used on big boats all of the time, not
>only to do AC work but also refer work. Some also heat the hotwater.
>Most run one compressor on the main engine and one on the genset.
>Holler if you would like some links on this concept. I too have crazy
>ideas.
>
>Take Care
>Arch
>
>In a message dated 4/22/99 9:41:34 PM Central Daylight Time,
travism
>writes:
>
>>
>> I have dreamed of building an "integrated" system that would use one
large
>> condenser, the dash evaporator and a rear evaporator, and two
>> compressors...the A-6 that is engine mounted and parallel it with a
>hermetic
>> electric. Each compressor's check valves would keep it from being a
problem
>> when the other was running. You'd have to have a large electric fan to
cool
>> the condenser when running on 120 volts. But this would get rid of the
need
>> for the noisy protruberances on the roof.
>>
>
>
 
Arch --

I'd say almost any of the Sankyo's, or the newer GM stuff can retro-fit with
the right brackets.
One nice thing about the A6's is they've got good capacity at low speeds. I
think they consume about 4HP, so the savings may not be high switching to a
radial or rotary. Something to think about though. A rotary would take less
power, but perhaps 'run' longer.

I've just about burnt out my brain cells thinking about Travis's idea, but
I'd check out Vintage Air's site: http://www.vintageair.com/ I helped put
one of their units in a Cord 812 last summer. Very high quality stuff.

I'll also see what's new at Acme Recreational air in Goshen tomorrow and
report back.
(More in our price range.)

Mark

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Gcbr
> Sent: Thursday, April 22, 1999 9:48 PM
> To: gmcmotorhome
> Subject: Re: GMC: A.C. Compressor (trivia)
>
>
> Mark
>
> WOW! Thanks for the lesson. My question is this. My SOB has a rotary
> compressor. An SD-5 to be exact. I know the rotary compressors use less
> horsepower. My question is there a rotary compressor out there that will
> power our GMCs?
>
> Take Care
> Arch 76 GB IL
>
> In a message dated 4/22/99 9:28:18 PM Central Daylight Time,
> mgrady

>
> >
> > I worked on many full sized GM cars that frequently had problems due to
> > smallish condensers (by design) and would tend to pop off
> refrigerant when
> > the fan clutches got 'lazy'. Further, by having the evaporator
> flooded with
> > liquid refrigerant, evap cores frequently 'rotted' out from
> the inside out.
> > This was because super heated R-12 would reduce the receiver dryer's
> ability
> > to keep even the smallest amount of moisture out of the system
> and held in
> > the desiccant. The resulting acid ate through aluminum
> evaporators like a
> > knife through butter.
> >
> > End of the history lesson.
> >
>
 
Hi Travis,

I have been working toward your dream A/C system with an added twist.

The A-6 is good for 36,000 btu conservative, but I found a bus A/C unit
rated 50,000 btu using our same old A-6 compressor.

Last summer I replaced both rooftop A/C units with vents, Max covers and
fans. My vents stayed open all summer and there were no problems with water
entry. We had some thunderstorms with high winds so there were several good
tests. It stayed surprisingly cool inside most days.

My system will use the A-6 as my sole compressor.

On shorepower I will power it with a 2 hp 120 volt dual capacitor motor.
Plans are to add a 2nd V belt sheave on a shaft extension screwed into the
1/2" pipe threads on the front of the A-6 shaft.

I think this will be workable, if not my backup with shorepower is a 120
volt compressor from a window A/C with check valves in the high pressure
lines. (Similar to what you mention)

I plan to use a second similar size condenser to supply my rear evaporator.
Together these two condensers have more capacity than any large single unit
I could find.

An inexpensive common 120v box fan in front of the condensers will cool them
when on shorepower.

Hopefully I'll get the entire project finished this summer. I'm hanging on
to my rooftop units in case there is an oversight and I have to back out of
my A/C modifications.

Don Miller (in the experimental mode)
75 Glennbrook project
Shenandoah Valley of Virginia

Travis said:

> I have dreamed of building an "integrated" system that would use one large
> condenser, the dash evaporator and a rear evaporator, and two
> compressors...the A-6 that is engine mounted and parallel it with a
hermetic
> electric. Each compressor's check valves would keep it from being a
problem
> when the other was running. You'd have to have a large electric fan to
cool
> the condenser when running on 120 volts. But this would get rid of the
need
> for the noisy protruberances on the roof.
>
> Perhaps the condenser for this arrangement could be somewhere besides in
> front of the radiator, though I don't see why the present location
wouldn't
> be just fine.
>
> Any thoughts on this?
>
> Travis
 
Travis & Arch --

Solid ideas, cool! (pun intended) That would make the Suburban/Astro/Savanna
rear A/C unit seem to be the logical choice, since you could mount it in the
ceiling close to where the rear Duo-therm is now. You'd have to plumb it of
course, perhaps with nylon barrier hose. You'd also have to drain the
condensate, easy to do.

I haven't looked at the design of one of these recently but I doubt they've
changed much. I'm getting junk yard fever. Now if we get a day it doesn't
rain...

Now, I gotta' see how to convert my 6K Onan to 220 to run a 3ton sealed
compressor... and see how my supply of pure grade 'research' R-12 is holding
out.

Mark

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Gcbr
> Sent: Thursday, April 22, 1999 11:01 PM
> To: gmcmotorhome
> Subject: Re: GMC: A.C. Compressor (trivia)
>
>
> Travis
>
> No reason to not chase this. It will take some work. Now as to
> the location
> of the other evaporator. You want the intake as high as you can get it.
> Hot air rises like the balloons do. It will stay trapped there
> unless of suck
> it down to the evaporator. One thing good I can say good about my SOB
> is that the AC air intake is in the ceiling--------keeps the
> beast real cool.
> Hottest air is taken into the evap and spit out on high. Good design.
>
> Take Care
> Arch
>
> In a message dated 4/22/99 10:45:24 PM Central Daylight Time,

>
> >
> > The principle is sound. Shouldn't take a lot of design work to make
> > practical. Now wouldnt this be a dream? A GMC coach with a
> slick top, no
> > noise from the roof ac units...cold air from the dash
> registers and from a
> > concealed unit, say about where the oven is now. A 5HP
> hermetic compressor
> > under the hood out of the way. Under way, the engine powers it. Parked,
> > shore power or genset runs the hermetic. Sounds sweet to me.
> Any reason not
> > to pursue this?
> >
>
 
I'd say this is one very good solution. I used the area above me
refrigerator as a convection cool 'channel' for the refrigerator (I'm still
using the original 12v only model).

That would be close to the center Duo-therm location though, add one in the
back and you're in pretty good shape.

Now, how much do you suppose these cost at the salvage yard?

Mark

> -----Original Message-----
> From: owner-gmcmotorhome
> [mailto:owner-gmcmotorhome]On Behalf Of Travis Martin
> Sent: Thursday, April 22, 1999 7:01 AM
> To: gmcmotorhome
> Subject: Re: GMC: A.C. Compressor (trivia)
>
>
> Okay, since all we are having to locate is the evaporator and its fan, how
> about the space above the refrigerator? For that matter, I don't suppose
> there's any limit to how many evaporators one could install other than the
> practical considerations. Possibly two small evaporators instead of one
> larger one? The Frigidaire units, complete with blowers, that are factory
> installed on practically every Suburban down here are small...about six
> inches tall, eighteen wide and twelve deep, including the blower, and come
> with an expansion valve installed...all we would have to worry about would
> be refrigerant piping and building a suitable enclosure and ductwork.
>
> Travis
>
> -----Original Message-----
> From: Gcbr
> To: gmcmotorhome
> Date: Thursday, April 22, 1999 11:07 PM
> Subject: Re: GMC: A.C. Compressor (trivia)
>
>
> >Travis
> >
> >No reason to not chase this. It will take some work. Now as to
> the location
> >of the other evaporator. You want the intake as high as you can get it.
> >Hot air rises like the balloons do. It will stay trapped there unless of
> suck
> >it down to the evaporator. One thing good I can say good about my SOB
> >is that the AC air intake is in the ceiling--------keeps the beast real
> cool.
> >Hottest air is taken into the evap and spit out on high. Good design.
> >
> >Take Care
> >Arch
> >
> >In a message dated 4/22/99 10:45:24 PM Central Daylight Time,

> >
> >>
> >> The principle is sound. Shouldn't take a lot of design work to make
> >> practical. Now wouldnt this be a dream? A GMC coach with a
> slick top, no
> >> noise from the roof ac units...cold air from the dash
> registers and from
> a
> >> concealed unit, say about where the oven is now. A 5HP hermetic
> compressor
> >> under the hood out of the way. Under way, the engine powers
> it. Parked,
> >> shore power or genset runs the hermetic. Sounds sweet to me.
> Any reason
> not
> >> to pursue this?
> >>
> >
> >
>
 
Travis

I keep getting this response from your email server:

:
208.234.228.206 does not like recipient.
Remote host said: 550 you are not allowed to send mail to
Giving up on 208.234.228.206.

I haven't ever got a error message quite like this one.

I'm trying with another return address, thinking that door.net might've
recieved some spam at some time or another from someone and
thus have quit accepting mail from that address. (Tried it and it doesn't
work either!)

This is really strange! (sctratchin my head)

Please respond to my personal email address. bdub or
bmassey

bdub
'76 Palm Beach
In The Heart o Texas
www.web-access.net/~bmassey/
icq # 202333

>Don't know why it bounced...that's the right address. ISP may have had a
>problem. Please try again
>
>Travis
>
>
>-----Original Message-----
>From: Billy Massey
>To: gmcmotorhome
>Date: Thursday, April 22, 1999 11:38 PM
>Subject: Re: GMC: A.C. Compressor (trivia)
>
>
>>Travis, what's your email addy? I sent you a note at travism and
>>it bounced back to me.
>>

>>
>>
>>bdub
>>'76 Palm Beach
>>In The Heart o Texas
>>www.web-access.net/~bmassey/
>>icq # 202333
>>
>
>
 
This is exactly what I have trying to do the research on for my 'Transmode
- -to-Motorhome' conversion. I had started a thread about 6 weeks ago
looking for info on this type of setup. Me goal is to keep my coach
without anything on the roof (that's the way it is now). I will be a very
willing guinea pig for this and I have a budget to spend. (wife
continually reminds me about how hot New Mexico can be in October).

>Arch, thanks for the note. I didn't realize that this was common practice on
>boats. Not many boats around here, and none that I know of with AC...
>
>Dual evaporators, on the other hand, are extremely common. Almost all
>Suburbans and vans have rear evaporators. And the Suburban is the National
>Car of Texas.
>
>The principle is sound. Shouldn't take a lot of design work to make
>practical. Now wouldnt this be a dream? A GMC coach with a slick top, no
>noise from the roof ac units...cold air from the dash registers and from a
>concealed unit, say about where the oven is now. A 5HP hermetic compressor
>under the hood out of the way. Under way, the engine powers it. Parked,
>shore power or genset runs the hermetic. Sounds sweet to me. Any reason not
>to pursue this?
>
>Travis
>-----Original Message-----
>From: Gcbr
>To: gmcmotorhome
>Date: Thursday, April 22, 1999 10:12 PM
>Subject: Re: GMC: A.C. Compressor (trivia)
>
>
>>Travis
>>
>>I have some good theory for you. Fact there have been more than one unit
>>built with more than one evaporator. Theory at 12 cb.in. you should be able
>>to get close to 60,000 btus out of it (dont have books in front of me).
>>The 2 compressor arrangement is used on big boats all of the time, not
>>only to do AC work but also refer work. Some also heat the hotwater.
>>Most run one compressor on the main engine and one on the genset.
>>Holler if you would like some links on this concept. I too have crazy
>>ideas.
>>
>>Take Care
>>Arch
>>
>>In a message dated 4/22/99 9:41:34 PM Central Daylight Time,
>travism
>>writes:
>>
>>>
>>> I have dreamed of building an "integrated" system that would use one
>large
>>> condenser, the dash evaporator and a rear evaporator, and two
>>> compressors...the A-6 that is engine mounted and parallel it with a
>>hermetic
>>> electric. Each compressor's check valves would keep it from being a
>problem
>>> when the other was running. You'd have to have a large electric fan to
>cool
>>> the condenser when running on 120 volts. But this would get rid of the
>need
>>> for the noisy protruberances on the roof.
>>>
>>
>>
>
 
Travis,

Not a lot of data on the site, but a few days ago I posted this URL of a
firm in Greece who builds bus roof top air conditioners. Their 50,000 btu
Tropical model uses our A6 compressor.

http://www.otenet.gr/tropical/products.html

Converting from the metric data it looks like their 50,000 btu bus unit
moves 1353 cfm air through the evaporator and 2917 cfm air through the
condenser.

I had calculated the A-6 pumped enough freon to supply 36,000 btu with
engine idling in neutral. I don't have volumetric efficiency data for this
compressor but I think my guess must be conservative. Volumetric efficiency
will also vary with compressor speed. Anyway it should pump enough freon.

Still trying to find a suitable ball bearing centrifugal clutch to use on
the electric motor though could just let it freewheel.

Existing A/C control system will be used but a SPDT switch will route the dc
control voltage to the compressor clutch when 455 engine is running or when
on shorepower, to a relay controlling the 120v motor.

I installed a U Line Icemaker Refrigerator combination which is shorter than
the OEM refrigerator. This leaves plenty of room above refrigerator for our
TV facing forward and the second evaporator. I'll duct air from evaporator
into the head and plan to run one or more ducts aft into the rear area.

Anyone know how Suburban rear unit capacity compares to a typical automotive
front unit ? I want this system to have adequate capacity throughout.

Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia

>>>
I like it! This solves the oil control issue that Mark referred to; only one
compressor with dual power sources. The electric motor can simply
"freewheel" when the compressor is powered off of the engine, and the clutch
is open when powered by the electric motor.

If we keep it up, we just might come up with a good idea. Can you elaborate
a bit on the bus AC that you mention? I'd like to know how the did it.

Travis
>>>>
 
These unit look a lot like the ones I see on the Mexican busses. I guess I
will have to pay closer attention next time.

Jack
1977 (transmode)

- -----Original Message-----
From: owner-gmcmotorhome
[mailto:owner-gmcmotorhome] On Behalf Of Donald W. Miller
Sent: Friday, April 23, 1999 2:37 PM
To: gmcmotorhome
Subject: Re:GMC: A.C. Compressor (trivia)

Travis,

Not a lot of data on the site, but a few days ago I posted this URL of a
firm in Greece who builds bus roof top air conditioners. Their 50,000 btu
Tropical model uses our A6 compressor.

http://www.otenet.gr/tropical/products.html

Converting from the metric data it looks like their 50,000 btu bus unit
moves 1353 cfm air through the evaporator and 2917 cfm air through the
condenser.

I had calculated the A-6 pumped enough freon to supply 36,000 btu with
engine idling in neutral. I don't have volumetric efficiency data for this
compressor but I think my guess must be conservative. Volumetric efficiency
will also vary with compressor speed. Anyway it should pump enough freon.

Still trying to find a suitable ball bearing centrifugal clutch to use on
the electric motor though could just let it freewheel.

Existing A/C control system will be used but a SPDT switch will route the dc
control voltage to the compressor clutch when 455 engine is running or when
on shorepower, to a relay controlling the 120v motor.

I installed a U Line Icemaker Refrigerator combination which is shorter than
the OEM refrigerator. This leaves plenty of room above refrigerator for our
TV facing forward and the second evaporator. I'll duct air from evaporator
into the head and plan to run one or more ducts aft into the rear area.

Anyone know how Suburban rear unit capacity compares to a typical automotive
front unit ? I want this system to have adequate capacity throughout.

Don Miller
75 Glennbrook project
Shenandoah Valley of Virginia

>>>
I like it! This solves the oil control issue that Mark referred to; only one
compressor with dual power sources. The electric motor can simply
"freewheel" when the compressor is powered off of the engine, and the clutch
is open when powered by the electric motor.

If we keep it up, we just might come up with a good idea. Can you elaborate
a bit on the bus AC that you mention? I'd like to know how the did it.

Travis
>>>>
 
Good points, Rick. But I don't think overspeeding the motor would be a
problem. A sqirrel cage induction motor's armature is really quite simple
and should be able to take several thousand RPM without problem. My guess is
that we'd use a 1725 RPM motor of about 2 HP and couple it to the compressor
1:1

I'm guessing that the ratio from the crank pulley to the compressor is not
more than 2:1, so at 4000 engine RPM, the compressor and thus the electric
motor will be turning not more than 8000 RPM. Actually, I don't think the
ratio is that high and thus the speed would be somewhat lower, so I don't
think this will be a problem, particularly since this is a rare occurrence
and not held for long.

But everyone who is interested in this idea needs to keep playing the "what
if" and "worst case" game...

A big part of what makes this a neat idea to me is the prospect of
eliminating the roof units altogether...thus the interest in using the space
over the refrigerator. Top of the wardrobe might possibly work too, though
it would be better to leave it open.

Travis
- -----Original Message-----
From: RickStapls
To: gmcmotorhome
Date: Friday, April 23, 1999 12:26 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>
>> My system will use the A-6 as my sole compressor.
>>
>> On shorepower I will power it with a 2 hp 120 volt dual capacitor motor.
>> Plans are to add a 2nd V belt sheave on a shaft extension screwed into
the
>> 1/2" pipe threads on the front of the A-6 shaft.
>
>Donald,
> I like this idea, but my concern would be overspeeding the 120V motor
when
>the 455 hits 4000 rpm with the AC on. I'd feel better if I could use dual
>clutches or an overrunning clutch or sumthin'.
>
> I'm enjoying this thread, and want to toss in a few ideas, FWIW:
>
>1 What about supplying one (or even both) roof AC units with freon from
>the A-6? Since they're already located in the "right" place (up high) to
>suck out the hot air, and take up NO precious interior space, they might be
>just the ticket. You'd have to replace the blower motor(s) with a 12V, or
>feed it from an inverter, but otherwise it's just a matter of plumbing and
>wiring. (Or so I think...?) Along this line, would it make any sense to
>have the A-6 pump high-pressure freon to the roof AC(s), and use the roof
>condenser(s) to expel the heat, keeping it out of the engine compartment?
>Would this work?
>
>2 OTOH, I too would like a lower, cleaner roofline (recalling squeezing
>under a 9' 6" railroad bridge in Amherst, Mass, when last we visited my old
>home area......). I too have been eyeing the oven as a possible location.
>(I want a heater core in there as well.) There is space behind the
built-in
>wardrobe drawers where you might run a duct to pick up hot air off the
>ceiling. Don't know if you could get past the drain vent stack, or if
>there's room for a cold duct too, but maybe worth investigating.
>
>3 I too have eyed the space over the refrigerator as a possible AC space,
>but when I pulled my Norcold 462 ("...'tis neither hot, Norcold.") last
>summer to convert it into a 463 (3-way), I discovered the space is pretty
>limited up there. The curve of the roof brings it down close to the refer,
>and I'd be leary of constricting the airflow through there. Maybe it's
>possible.....
>
>4. If you use a box fan in front of the radiator, remember they aren't
very
>weatherproof. Not only does it get road-splashed, but the dash AC
evaporator
>drips its condensate on it (helps cool the condenser too). Stock GMC fan
>probably consumes 10+ hp when hot and locked up. Don't mean to say it
can't
>be done, only it won't be easy.
>
>5 One more location for a second (or third! Thanks for the idea,
netizens!)
>evaporator is over the rear window (where GM put the optional fishing-rod
>cabinet). You'd have to make sure it cleared the emergency exit ring on
the
>window, and plumbing and wiring would be long, but it's a little-used high
up
>spot.
>
>Just some brain-balls to bounce around....
>
>Rick Staples
>'75 Eleganza
>Louisville, CO
>
>
 
Hi, Arch,

You're probably right about wanting to run it faster...I'm guessing 1725 is
about what it is used to running at a fast idle. That would be plenty to do
a good job with just the dash evaporator, but since the whole object of this
exercise is to add a couple of rear evaporators, it would likely be
disappointing unless run a bit faster.

I still don't think that the turning of the motor's armature is going to
hurt anything; there's nothing there to hurt.

My biggest concern with leaving the motor hooked permanently to the
compressor without an overrunning clutch is the considerable inertia that
this adds. If, as I assume, the GMC is of the CCOT (compressor cycles on and
off) type, then the compressor clutch can be expected to engage at speed.
This is going to be hell on clutches and belts if in addition to the
compressor the clutch is having to spin up the armature of the electric
motor. There isn't any need for an electric clutch for the motor, but a
sprag would be great.

Travis

- -----Original Message-----
From: Gcbr
To: gmcmotorhome
Date: Friday, April 23, 1999 7:03 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>Travis
>
>To get the A-6 to put out a lot of good cool you will want to turn it a
>little faster
>than 1725. Consider using another ac clutch on the electric motor so the
>armature is not driven to 8000 rpm.
>
>Take Care
>Arch 76 GB IL
>
>In a message dated 4/23/99 6:22:15 PM Central Daylight Time,
travism
>writes:
>
>>
>> I'm guessing that the ratio from the crank pulley to the compressor is
not
>> more than 2:1, so at 4000 engine RPM, the compressor and thus the
electric
>> motor will be turning not more than 8000 RPM. Actually, I don't think
the
>> ratio is that high and thus the speed would be somewhat lower, so I
don't
>> think this will be a problem, particularly since this is a rare
occurrence
>> and not held for long.
>>
>
>
 
Hi, Arch,

True, that would work well. But if a suitable overrunning clutch could be
fitted to the motor, it would be simpler since it wouldn't require a circuit
to energize it and should also be simpler to mount. The problem is finding
one suitable for the task that doesn't break the budget!

Since the only downside mentioned so far is the possibility of oil
distribution problems, we don't need to completely abandon the concept of
using a second compressor...presumably a hermetic. For that matter, we could
use a second A-6, powered by the electric motor. Not as elegant or as
compact, but should work.

Hermetics tend to be quiet, compact, and reliable.

Travis

- -----Original Message-----
From: Gcbr
To: gmcmotorhome
Date: Friday, April 23, 1999 9:57 PM
Subject: Re: GMC: A.C. Compressor (trivia)

>Travis
>
>If you had an AC clutch on the electric motor you would not have
>the problem with start up of the armature----all you would be starting
>is the outer clutch. Just Theory.
>
>Take Care
>Arch
>
>In a message dated 4/23/99 9:43:50 PM Central Daylight Time,
travism
>writes:
>
>> off) type, then the compressor clutch can be expected to engage at speed.
>> This is going to be hell on clutches and belts if in addition to the
>> compressor the clutch is having to spin up the armature of the electric
>> motor. There isn't any need for an electric clutch for the motor, but a
>> sprag would be great.
>>
>> Travis
>>
>
>
 
You must log in or register to reply here.
Get your shine on at www.cruzingear.co
Applied GMC

Share this page

Share this page
Top Bottom
Back