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Duo-Therm refrigerant and charge amount [message #304263]

Tue, 26 July 2016 11:43

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

I'm planning on brazing in access valves to the Duo-Therm on my 78 Royale and recharging it with propane or propane/isobutane, as appropriate. Does anyone know what refrigerant (R-12 or R-22) is used in these, and what is the total charge amount? Thank you

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Re: Duo-Therm refrigerant and charge amount [message #304268 is a reply to message #304263]

Tue, 26 July 2016 12:18

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

gladius wrote on Tue, 26 July 2016 11:43

I'm planning on brazing in access valves to the Duo-Therm on my 78 Royale and recharging it with propane or propane/isobutane, as appropriate. Does anyone know what refrigerant (R-12 or R-22) is used in these, and what is the total charge amount? Thank you

The type of refrigerant is on page 24E-2 of Maintenance Manual X7525 available here:

http://www.gmcmi.com/wp-content/uploads/2014/05/X7525_75-76-maint-manual.pdf

It doesn't say how much, but the MM says:

"Be sure to measure the charge accurately. The specification is critical with the capillary tube metering system. Each air conditioning unit has an identification tag that specifies the exact charge for that unit."

I guess if that tag is visible, it will tell you what refrigerant to use. The MM also contains detailed instructions for pressures and what-not.

The short answer is to Ref The Fine Manual.

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Re: [GMCnet] Duo-Therm refrigerant and charge amount [message #304271 is a reply to message #304268]

Tue, 26 July 2016 12:25

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

The original DuoTherm roof air conditioners used R22 refrigerant. I don't know the quantity.

Since they are a sealed unit it would be rare got any to leak out. If one has a leak it all would've gone.
It is it like the dash air conditioner where you have a compressor clutch seal or hose connections that can leak a small amount.

Emery Stora

> On Jul 26, 2016, at 11:18 AM, A. wrote:
>
> gladius wrote on Tue, 26 July 2016 11:43
>> I'm planning on brazing in access valves to the Duo-Therm on my 78 Royale and recharging it with propane or propane/isobutane, as appropriate.
>> Does anyone know what refrigerant (R-12 or R-22) is used in these, and what is the total charge amount? Thank you
> The type of refrigerant is on page 24E-2 of Maintenance Manual X7525 available here:
>
> http://www.gmcmi.com/wp-content/uploads/2014/05/X7525_75-76-maint-manual.pdf
>
> It doesn't say how much, but the MM says:
>
> "Be sure to measure the charge accurately. The specification is critical with the capillary tube metering system. Each air conditioning unit has an
> identification tag that specifies the exact charge for that unit."
>
> I guess if that tag is visible, it will tell you what refrigerant to use. The MM also contains detailed instructions for pressures and what-not.
>
> The short answer is to Ref The Fine Manual.
> --
> 73 23' Sequoia 4 Sale
> 73 23' CanyonLands Parts Unit 4 Sale
> Upper Alabama
> "Highest price does not guarantee highest quality."
>
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Re: Duo-Therm refrigerant and charge amount [message #304278 is a reply to message #304263]

Tue, 26 July 2016 13:35

Adrien G.

Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624

Karma: 1

Senior Member

IIRC a while back of a thread here on this subject. and that person did make the change to Duracool HC22a.
If my thinking is right, the final suction side pressure was 73 psi., with an improvement in the cold air output.

I don't recall who or exactly how far back that thread was. I'm also interested in doing this type of change.

FWIW

Adrien & Jenny Genesoto 75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6

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Re: Duo-Therm refrigerant and charge amount [message #304285 is a reply to message #304278]

Tue, 26 July 2016 15:39

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

Adrien G. wrote on Tue, 26 July 2016 13:35

IIRC a while back of a thread here on this subject. and that person did make the change to Duracool HC22a.
If my thinking is right, the final suction side pressure was 73 psi., with an improvement in the cold air output.

I don't recall who or exactly how far back that thread was. I'm also interested in doing this type of change.

FWIW

There's this thread: http://gmc.mybirdfeeder.net/GMCforum/index.php?t=msg&goto=213099&rid=2083&srch=r-22#msg_213099

Final result is at the end of the thread.

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Re: Duo-Therm refrigerant and charge amount [message #304339 is a reply to message #304263]

Wed, 27 July 2016 11:27

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

Thanks for the helpful information everyone. I'll hold off on the recharging for the moment as the unit is working fine, and there's higher items on the priority list. At first I thought the unit was bad, but it just needed 2 minutes for the delay relay to switch on. The one unit kept the front 3/4 of the coach comfortable yesterday in 100 degree heat, and froze me out at night.

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Re: Duo-Therm refrigerant and charge amount [message #304387 is a reply to message #304263]

Wed, 27 July 2016 20:50

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

These are called hermetically sealed units. If they don't leak, they don't leak. All dash air systems are automotive type and all leak by design. There are specs on what a normal leak rate is in a vehicle's FSM. Back to the DuoTherm R22 unit. Sounds like your system has not lost it's charge. For future reference R22 is still readily avalable and cost not an issue in the small ammounts needed. I would not go to a HC drop in on a hermetic system since the electric motor section of the compressor is exposed to the refigerant path.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: Duo-Therm refrigerant and charge amount [message #304539 is a reply to message #304263]

Fri, 29 July 2016 13:59

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

I don't see how a hydrocarbon refrigerant could possibly harm the motor. R600a is widely used in European refrigerators which are also hermetically sealed. It doesn't matter if R22 is 10 cents a pound; I won't support DuPont, or use any other patented or poisonous refrigerant. Confused

Confused

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Re: Duo-Therm refrigerant and charge amount [message #304565 is a reply to message #304263]

Fri, 29 July 2016 21:19

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

I thought R12 and R22 are largely non poisonous. It displaces oxygen when in high concentrations and therefore can cause oxygen starvation. The catalytic effect on the ozone layer is a reletively recent discovery in the time frame of the CFCs. They were used largely in manufactuing processes and as propellant prior to discovery of the ozone issue were free air vented as common practice. Since this has stopped for the most part, the ozone layer is doing some remarkable healing.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: Duo-Therm refrigerant and charge amount [message #304570 is a reply to message #304565]

Fri, 29 July 2016 22:49

Norisan

Messages: 18
Registered: April 2015
Location: Calgary

Karma: 0

Junior Member

Although CFCs are not considered to be poisonous, when burned they produce a nasty gas called phosgene which was used as a chemical weapon in WW1.

Norm.

[Updated on: Fri, 29 July 2016 22:53]

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Re: Duo-Therm refrigerant and charge amount [message #304576 is a reply to message #304570]

Sat, 30 July 2016 08:25

Jp Benson

Messages: 649
Registered: October 2011
Location: Fla

Karma: 2

Senior Member

The refrigerant charge is usually shown on the nameplate. A refrigerant other than R22 will probably require a different amount as it will have a different specific heat and boiling point. If it's not leaking I would not open it up. Especially if I didn't have the means to recycle.

Freon was once widely use as a cleaning fluid in the manufacture of electronic components. I once worked at a location where they used a flatbed truckload of 55 gallon drums of Freon every month. All vented into the atmosphere.

JP

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Re: Duo-Therm refrigerant and charge amount [message #304578 is a reply to message #304263]

Sat, 30 July 2016 08:52

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

Exactly. The huge amounts used as automotive refrigerant were dwarfed by industrial uses. And yes on the deadly phosgene. I was considering a person using it in a non combustion state. I hear 134a is very bad health wise though less ozone damaging.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: Duo-Therm refrigerant and charge amount [message #304642 is a reply to message #304578]

Sun, 31 July 2016 16:30

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

"The catalytic effect on the ozone layer is a reletively recent discovery in the time frame of the CFCs."

Discovery...or total fabrication?

"They were used largely in manufactuing processes and as propellant prior to discovery of the ozone issue were free air vented as common practice. Since this has stopped for the most part, the ozone layer is doing some remarkable healing."

Isn't it convenient that the ozone hole decided to locate itself over Antarctica, where you or I cannot confirm or deny its actual existence?

Funny that much of the rest of the world still uses CFCs, such as China which is now the largest economy in the world, and yet somehow the "ozone hole" is said to be shrinking. I guess the Chinese R12 isn't harmful to the ozone layer. You'd think the existence of a hole in the ozone layer would continue to be alarming news, but it's funny that all mentions of it disappeared from the news media after R12 was successfully phased out.

I think it's far more likely that the "ozone hole" was a convenient excuse to mandate the changeover to DuPont's newest patented refrigerant (R134a) after their R12 patents expired. The new boogeyman is "global warming" aka global cooling, aka climate change, aka catastrophic climate disruption, which will of course mandate a shift to whatever new patented refrigerant DuPont has prepared for us.

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Re: Duo-Therm refrigerant and charge amount [message #304643 is a reply to message #304576]

Sun, 31 July 2016 16:36

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

"If it's not leaking I would not open it up. Especially if I didn't have the means to recycle."

The best way to recycle patented, poisonous refrigerants is to ventilate them to the atmosphere, where they will never be seen or heard from again, and never have the opportunity to contaminate someone else's refrigeration system. Let mother nature do the recycling. Smile

Smile

I'd much rather open up the system to charge with a new refrigerant and install an access valve for future service on my own time and terms, rather than waiting until a problem develops in the middle of summer, where I get to do the same job in 100+ degree heat. I'll keep using the unit as-is for now, but this fall it's getting charged with propane. Cool

Cool

[Updated on: Sun, 31 July 2016 16:36]

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Re: [GMCnet] Duo-Therm refrigerant and charge amount [message #304644 is a reply to message #304642]

Sun, 31 July 2016 17:00

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

G'day,

You think that the ozone layer hole might have something to do with this?

Australia has a very high - and increasing - rate of melanoma. In 2012, deaths from melanoma occurred in 7.3-9.8 per 100,000
population. In Australia, melanoma is the third most common cancer in either sex; indeed, its incidence is higher than for lung
cancer, although the latter accounts for more deaths. It is estimated that in 2012, more than 12,000 Australians were diagnosed with
melanoma: given Australia's modest population, this is better expressed as 59.6 new cases per 100,000 population per year; >1 in 10
of all new cancer cases were melanomas.[86] Melanoma incidence in Australia is matter of significance, for the following reasons:

Australian melanoma incidence has increased by more than 30 per cent between 1991 and 2009.
Australian melanoma age-standardised incidence rates were, as of 2008, at least 12 times higher than the world average.
Australian melanoma incidence is, by some margin, the highest in the world.
Overall age-standardised cancer incidence in Australia is the highest in the world, and this is attributable to melanoma alone.
Age-standardised overall cancer incidence is similar to New Zealand, but there is a statistically-significant difference between
Australia and all other parts of the developed world including North America, Western Europe, and the Mediterranean.

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Nathan Cline
Sent: Monday, August 01, 2016 7:30 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Duo-Therm refrigerant and charge amount

"The catalytic effect on the ozone layer is a reletively recent discovery in the time frame of the CFCs."

Discovery...or total fabrication?

"They were used largely in manufactuing processes and as propellant prior to discovery of the ozone issue were free air vented as
common practice.
Since this has stopped for the most part, the ozone layer is doing some remarkable healing."

Isn't it convenient that the ozone hole decided to locate itself over Antarctica, where you or I cannot confirm or deny its actual
existence?

Funny that much of the rest of the world still uses CFCs, such as China which is now the largest economy in the world, and yet
somehow the "ozone hole" is said to be shrinking. I guess the Chinese R12 isn't harmful to the ozone layer. You'd think the
existence of a hole in the ozone layer would continue to be alarming news, but it's funny that all mentions of it disappeared from
the news media after R12 was successfully phased out.

I think it's far more likely that the "ozone hole" was a convenient excuse to mandate the changeover to DuPont's newest patented
refrigerant (R134a) after their R12 patents expired. The new boogeyman is "global warming" aka global cooling, aka climate change,
aka catastrophic climate disruption, which will of course mandate a shift to whatever new patented refrigerant DuPont has prepared
for us.
--
Gadsden, AL

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: [GMCnet] Duo-Therm refrigerant and charge amount [message #304654 is a reply to message #304644]

Sun, 31 July 2016 18:30

k2gkk

Messages: 4452
Registered: November 2009

Karma: -8

Senior Member

Due to elliptical orbit of Earth around Sun an ~ 23 degree tilt of Earth's axis, southern hemisphere gets higher dose of solar radiation in Summer there. Add the typical inclination of Aussies for suntans and the result is to be expected!

Mac in OKC, OK

Sent from my iPhone

On Jul 31, 2016, at 16:51, Rob Mueller wrote:

G'day,

You think that the ozone layer hole might have something to do with this?

Australia has a very high - and increasing - rate of melanoma. In 2012, deaths from melanoma occurred in 7.3-9.8 per 100,000
population. In Australia, melanoma is the third most common cancer in either sex; indeed, its incidence is higher than for lung
cancer, although the latter accounts for more deaths. It is estimated that in 2012, more than 12,000 Australians were diagnosed with
melanoma: given Australia's modest population, this is better expressed as 59.6 new cases per 100,000 population per year; >1 in 10
of all new cancer cases were melanomas.[86] Melanoma incidence in Australia is matter of significance, for the following reasons:

Australian melanoma incidence has increased by more than 30 per cent between 1991 and 2009.
Australian melanoma age-standardised incidence rates were, as of 2008, at least 12 times higher than the world average.
Australian melanoma incidence is, by some margin, the highest in the world.
Overall age-standardised cancer incidence in Australia is the highest in the world, and this is attributable to melanoma alone.
Age-standardised overall cancer incidence is similar to New Zealand, but there is a statistically-significant difference between
Australia and all other parts of the developed world including North America, Western Europe, and the Mediterranean.

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Nathan Cline
Sent: Monday, August 01, 2016 7:30 AM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Duo-Therm refrigerant and charge amount

"The catalytic effect on the ozone layer is a reletively recent discovery in the time frame of the CFCs."

Discovery...or total fabrication?

"They were used largely in manufactuing processes and as propellant prior to discovery of the ozone issue were free air vented as
common practice.
Since this has stopped for the most part, the ozone layer is doing some remarkable healing."

Isn't it convenient that the ozone hole decided to locate itself over Antarctica, where you or I cannot confirm or deny its actual
existence?

Funny that much of the rest of the world still uses CFCs, such as China which is now the largest economy in the world, and yet
somehow the "ozone hole" is said to be shrinking. I guess the Chinese R12 isn't harmful to the ozone layer. You'd think the
existence of a hole in the ozone layer would continue to be alarming news, but it's funny that all mentions of it disappeared from
the news media after R12 was successfully phased out.

I think it's far more likely that the "ozone hole" was a convenient excuse to mandate the changeover to DuPont's newest patented
refrigerant (R134a) after their R12 patents expired. The new boogeyman is "global warming" aka global cooling, aka climate change,
aka catastrophic climate disruption, which will of course mandate a shift to whatever new patented refrigerant DuPont has prepared
for us.
--
Gadsden, AL

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Re: [GMCnet] Duo-Therm refrigerant and charge amount [message #304655 is a reply to message #304654]

Sun, 31 July 2016 19:04

tphipps

Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL

Karma: 9

Senior Member

The
"replacement" for R134 is so dangerous that it will require total protection for workers who handle it. So corrosive, it will require total redesign and replacement of cooling systems to handle it. Bring on the Duracool.
Tom, MS II

2012 Phoenix Cruiser model 2552 KA4CSG

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Re: Duo-Therm refrigerant and charge amount [message #304662 is a reply to message #304565]

Sun, 31 July 2016 21:41

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

JohnL455 wrote on Fri, 29 July 2016 22:19

I thought R12 and R22 are largely non poisonous. It displaces oxygen when in high concentrations and therefore can cause oxygen starvation. The catalytic effect on the ozone layer is a reletively recent discovery in the time frame of the CFCs. They were used largely in manufactuing processes and as propellant prior to discovery of the ozone issue were free air vented as common practice. Since this has stopped for the most part, the ozone layer is doing some remarkable healing.

<Rant ON>
The man that wrote the original paper worked at the Space Physics Research Lab (aka SPRL) at U of Mich. He called us (yours truly and the late Orvil Feather) when he found out we were doing work with Ozone for water processing in Thetford's engineering group. He was afraid that he had made a error in the original paper and we ran several different experiments that confirmed what we had discovered and he and many others had missed.

Ozone is NOT O3.
Ozone is O++.

We were beat up by this a year before because we thought we knew what we were doing and we kept getting a 3 for 1 synergism. I used my engine emissions rack to confirm what the wet chemistry was saying.

He wrote another paper to confirm the error and nobody cared. The bad science stuck.

Another group at SPRL later confirmed that the lack of Ozone over the south pole is largely due to the polarity of the O++ Ozone atoms (not molecules) and the earth's magnetic and electrostatic fields.

Too bad nobody cares about that or any other good science....

Why haven't they banned CO2 fire extinguishers and carbonated beverages if CO2 is such a big issue???
<Rant Off>
Thank You All

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: Duo-Therm refrigerant and charge amount [message #304673 is a reply to message #304263]

Mon, 01 August 2016 08:55

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

And humans for expelling all that CO2 day and night. I wonder if what seems so be an increase in weeds is them thriving on CO2 surpluses.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: Duo-Therm refrigerant and charge amount [message #304677 is a reply to message #304263]

Mon, 01 August 2016 09:25

gladius

Messages: 48
Registered: November 2015

Karma: 0

Member

Aussie, I would guess that the surge in melanoma is probably linked to chemicals and/or radiation in the environment, just like so many other cancers that have been skyrocketing lately. We are being exposed to a lot of evil stuff that is destroying our health, with no help whatsoever being given from the government regulatory agencies that are supposed to be watchdogs to protect us. Same thing in the US and Australia, both countries being owned by the same corporations and banking families. Monsanto is feeding us GMO food which has been liberally sprayed with toxic glyphosate (Roundup), and now even produces Bt-toxin which slowly destroys the gut lining, causing auto immune disorders as the body attacks and destroys itself. All that's just fine according to the FDA, who assure us these GMO foods are perfectly safe. But just try selling raw milk in the USA and see how long it takes before they're knocking at your door with a cease and desist letter, or millions of dollars in fines.

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