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Mixing R12 With 134a, Yes We Can

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Old 08-15-09, 10:09 PM   #1
roedel
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Default Mixing R12 With 134a, Yes We Can

I posted this thread in another Lexus Forum, but it developed into such a heated debate that the moderator blocked my thread after two days.

So i am trying it here now, posting this not to convince anybody to do the same thing, i am posting to share my experience.
---------------------------------------------------------------------


Hello,

i am driving a 1990 LS400, in China, i love this car.
I bought it one year ago, last year the AC delivered ice cold air at max summer temperatures and humidity.
It gets hot and 100% humit here, crazy....

So this year i had to replace the compressor discharge hose and refilled the system with R12.
So far so good, the only thing i noticed was that the aircon did not blow as cold as before.
Low side and high side pressures were all within specs, strange.

Then i remembered that the previous owner told me his shop topped off the system with 134a..... back then i thought what the hack is he talking about.

Out of frustration i started to do some research and ohoooooo, found this Article:

Quote:
Posted by George Goble on June 19, 1999 at 21:14:44:
In Reply to: Re: Replacement of R12 with R406a posted by John Strauss on June 16, 1999 at 16:07:09:
As you stated, the EPA has now made it "illegal" to mix
different refrigerants in cars.. Last time I looked, it was
still legal to mix 'em in stationary equipment.
R-406A in various mixtures with R-12 were run in a fleet of Humvees
early on (ambulance bodies).. R-406A by itself gives a 6-8F colder
duct temps than R-12, so with 50/50 R-12/R-406A the performance
gain was about 3-4F or 1/2 of using pure R-406A. (before EPA mixing
ban).
The "shocker" in illegal mixing is that mixing Freeze12, FR-12,
or just R-134a with R-12 (computer simulation on what happens)
start out with one slowly leaking R-12 system, gets down to about
50% remaining charge when the owner decides a recharge is needed.
1) Assume owner just "tops off" with R-134a (system has mineral
oil that R-134a will not "carry", but 50% R-12 remains, so oil
return to the compressor works fine. R-134a and R-12 form an
"azeotrope" with a boiling point of around -31F (R12 is -21.7F,
(R-134a is -14.7F, Freeze12 is around -8F) at 1 ATM. This
results in a performance improvment (capacity increase 25% or so)
along with slightly higher head pressures.. Performance gain
(over R-12) is about 2/3 of the gain of using 100% R-406A.
Freeze12 (80% 134a/20% 142b) is similar, except 2-3F warmer
than the above.. still much better than total R-12. This
"good performaning" mixture is called "contamination" by those
with vested interests in preventing it.
2) Next summer, system low again, user tops it off with R-134a,
now there is 25% R-12 (still enough to carry oil fine) and
cooling is still better than R-134a.
3) 3rd summer.. system low again.. tops off again with R-134a,
12.5% R-12 remaining.. still returns mineral oil fine.. cooling
now is about R-12 performance..
4) 4th summer...system low again.. tops off again with R-134a..
about 6% R-12 left, marginal mineral return, but probably
will work.. R-134a cooling performance..
5) 5th summmer.. top off again.. 3% R-12 left.. oil fails to return
compressor siezes up and fails.. IF using Freeze12 instead,
performance will be about +15F warmer than R-406A (autofrost)
Look how well this "illegal contaminated system" worked.
Now if legal...
1) remove all R-12.. charge with R-134a or Freeze12..
and dont change the oil to POE.. (still is mineral).
performance: lower, 134a vs R-12..maybe 10F warmer..
If R-134a in mineral oil, compressor will fail within
1 week (or may go a couple of years if oil was changed to POE).
Freeze12 in mineral oil may run 3-4 months before compressor
gets "dry" enough to fail.
Doing things EPA legal is a "bad deal" when doing a "proper"
conversion to R-134a or Freeze12.. Illegal topping off gets much
better performance and 5 years of runtime...
go figure..
--ghg, inventor of R-406A (autofrost) and R-414A (GHG-X4)

Soooo, i recovered about one can of R12, dropped in one can of R134a and guess what, the system is back to live.
ICCCCCCE cold.

The compressor is still fine, even though the system was running with that mixture for years and there was absolutely no residue in the hoses and pipes.

I tought this might be interesting for anybody having a R12 system with low refrigerant level.
The only problem i see is that the R134a might cause corrosion, i read somewhere that this might be an issue.
But again, on my LS it did not cause any problem so far.

You cannot top of your 134a system with R12, the PAG oil would deteriorate in contact with R12!


I have to replace some O-rings soon and will switch to a Hydrocarbon Refrigerant.
It seems that the energy savings are amazing.
Already bought 5kg of R290 and R600a these two mixed at the correct ratio 80/20 should deliver a nice result.

Will post the outcome later
--------------------------------------------------

Exactly that hydrocarbon idea started a very emotional dialogue, some morons wishing me a firey death and an explosion ;-)
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Old 08-15-09, 11:08 PM   #2
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won't comment yet at least on the ideas you're presenting but i do think this belongs in the maint. forum since it isnt really specific to the LS.
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Old 08-16-09, 02:13 AM   #3
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i thought the fact that the r134a and r12 mixture did not corrode the system was ls specific, but i am not sure about that. can the thread be moved?

Last edited by roedel; 08-16-09 at 02:41 AM..
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Old 08-16-09, 07:24 AM   #4
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http://us.lexusownersclub.com/forums...howtopic=59559
no one wished u anything of the sort
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Old 08-16-09, 09:51 PM   #5
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it was my experience with my 90 ls400 as well. the other day my car A/C got gaz leak and stop cooling when I was going to a place 300km away from home. i went to a shop and get them to fill in 134a without fixing anything (i asked them fill 134a instead of r12 because i see a yeallow sticker under the hood: "134a only") after the 134a refill, a/c ran as if i was in ... winter. I drove home and few days after, gaz went out again. I had the a/c repaired completely, replaced new evap core, hoses etc. and the mechanic filled in r12. I told him that my car used 134a, he said NO, all your piping and valves are for r12, definitely not 134a. then he filled r12. The result is NOT good, temp at diffuser just drops to 8 degree C and no more.

i am just wondering if this is the case for 90LS400 where r12 can mix with 134a for better cooling?
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Old 08-17-09, 12:36 AM   #6
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When you mix R-12 and R-134a together, you'll form an azeotrope with totally different chemical and physical properties than either parent compound.
http://en.wikipedia.org/wiki/Azeotrope

PAG oils WILL degrade in the presence of R-12, they CANNOT tolerate chlorine - ever wonder why brake fluid(PAG based) will violently react with pool shock(Cl)? POE oil can be used in both R-12 and R-134a systems.

DuPont is marketing a R-134a and butane mix - but not in the US due to EPA and MACS regulations banning hydrocarbons in HVAC.
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Old 08-17-09, 03:41 AM   #7
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@qha_vn

sounds like my story, soembody most likely accidentally mixed R12 and R134 in your system.
So, if you have R12 in your system now, you can ask the shop to recover a bit R12 and top it off with r134a, voi la at least20% more performance.
the mixture will not damage your system since the shop should have used mineral oil.

anyway the shop will probably refuse to do so since mixing refrigerants is illegal in the states.

if you want to stay legal, you got to stick with r12 or as an alternative check if HC (propane) is legal in your state.

Last edited by roedel; 08-17-09 at 03:45 AM..
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Old 08-18-09, 12:22 AM   #8
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The fittings for R-12 and R-134A are different. How do you do it? R-12 now is very limited now, they are rare.

Fact: R-12 is actually better than R-134A. It's colder by a few degrees.
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Old 08-22-09, 05:32 PM   #9
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So i received my hydrocarbon gases, one bottle of R290 one bottle of R600a, superdry and 99.9% pure.
Mixed the following blend:
37% R600 (isobutane) + 63% R290(Propane).
The pressure of the blend at 86 deg F (28deg C) is at 104 psi.
Remark pure R290 propane has a pressure of 135 psi at the same temperature, adding 37% of R600 is reducing the pressure by 30psi.

I filled my Ac with 11.28 ounces (320 gram).
The LS usually takes 35.2 ounces (1000gram) of R12 gas.

I could load the complete batch in seconds, without starting the engine.
I started the car, the compressor kicked in, it sounds super smooth, the noise is more like a hisssssss than that grrrrrrr noise i had before.

That is due to the fact that the propane molecule is much bigger than the R12/R134 molecule, thus easier to compress.

My pressure readings: Low side 38psi, High side 150 psi.
With the R12/R134a blend i had 40psi/220psi.

Gotta check out why my low side readings are on the high side in either case, but i belief it is because of the gas mix.
The Lexus specs for R12 are 21-28psi low and 206-213 high.

I am getting a instand duct temperature of 53 degF (12Cels) on a 90 deg (33Celsius) super humid day. The condenser is not only dripping, water was running out the drain hose, i could fill a small coffee cup in about 1.5 minutes.

Once i put the system to recirculation the duct temp drops to 44 degF (7Celsius).

The performance of the system is exactly what i had with my high performance R12/R134a mix, but with much less strain on the compressor, the changes in pressure and compressor noise are obvious.
Not to mention the amount of engine power saved with the mix.

Another thing i noticed, when i switched on the AC at idle with R12 my idle Rpm was noticeably dropping before being raised by the ECU.
Now the idle RPM do not drop.

It is obvious that Hydrocarbons are an ideal and cheap Refrigerant for any AC, especially for old R12 systems.
If you switch your system to R134a you have nothing but disadvantages.

I spend the last few weeks researching this subject, all the rumors about the dangers of propane in a Ac system are Propaganda to say the least.
Just calculate how much money DuPont is going to loose if all cars would use Propane instead of their poison.

Yes 134a is poisonous and it burns releasing extremly toxic gases in the combination with the oil in the AC system, i will post some links later.

No accidents with Propane systems have ever been reported. Even though since the 1990's millions of vehicles have been converted.
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Old 08-22-09, 05:47 PM   #10
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Well I stopped reading after the original quoted message, but there alot more things to think about than oil getting back to the compressor...Each system is designed for a specific refrigerant. So, expansion valves, condensers, evaporators, and yes compressors are going to be different for each vehicle and each refrigerant. Yes the R.12 may carry oil back to the compressor, but assuming that year by year the r.12 charge will go down by a specified amount sounds spot on for an engineers "view of life". reality is you don't know how each system will react with both refrigerants. Most r.134a machines in use today already carry so much oil with their charge that there's no way you can guarantee no oil mixing. Plus no reputable technician will or should service an A/C system with using an identifier on it. And if the system is indeed contaminated...then they shouldn't touch it.

I am not discounting your personal experience, but what an engineer says "could" happen probably never does! trust me.

that's my 2 cents...
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Old 08-22-09, 06:05 PM   #11
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OK here some usefull links:

http://www.hydrocarbons21.com/
check out their knowledge base:
http://www.hydrocarbons21.com/papers.php

Quote:
hydrocarbons21.com aims to support the worldwide use of hydrocarbon refrigerants in cooling, refrigeration, and heating.
Please keep in mind that anybody could produce his hydrocarbon refrigerant, just like i did. The website has abviously no financial intrests in promoting these refrigerants.


I'am a ASE certified automotive master technician, you need knowledge and skills to work on your AC system, i assume no responsibility for what happens, including frostbite.


Attached a pdf about the usage and Risk of Hydrocarbon Refrigerants in Motor Cars for Australia and the United States:

Quote:
Commercial replacement of fluorocarbons in mobile air conditioning systems (MACS) with typically HC-290/600a[60/40] and minimal precautions began in Idaho in 1993. R290/600a has low environmental impact but mixed with air is flammable and frequencies for fire, injury and cabin overpressure were predicted. No such accidents are known from 1993 to mid-2003.

R290/600a suppliers consumption, representative MACS charges and charge termination frequency were used to predict yearly total MACS numbers. Mid-2002 in Australia there were 0.33106 and at end 2002 in the USA 4.7106 R290/600a MACS. Integrating over time gave usage for Australia to the end 2002 as 1.09106 car-years and to mid-2003 for the USA 21.7106 car-years.

The measured US fire, injury and cabin overpressure frequencies are less than 3.2 10−7 per car year with high probability. This fire frequency is a hundred times lower than predicted because most R290/600a leaks in MACS use are effectively nonflammable.



Dangers of 134a:

http://www.medhelp.org/posts/Respira...ak/show/283735


http://www.medhelp.org/posts/Respira...ak/show/283735

Quote:
> LETHAL R-134a CONCENTRATIONS IN PASSENGER COMPARTMENTS MAY OCCUR
> FROM EVAPORATOR FAILURE
>
> In August 1997, a study was done at the Armstrong laboratory, Wright
> Patterson Air Force Base, Dayton, OH. The report, "Human Inhalation of
> Halon 1301, HFC-134a and HFC-227ea for Collection of Pharmacokinetic
> Data" was authored by A. Vinegar, R. Cook, J McCafferty, M. Caracci, and
> G. Jepson.
>
> The concentration of R-134a being used was extremely low and (then
> thought) that nothing bad was going to happen. To quote from the bottom
> of page 10 (page 11 if abstract prepended), "Subject #3 was the first
> volunteer exposed to
>
> HFC-134a. The exposure concentration was 4000 ppm (0.4% v/v) and was
> scheduled to last for 30 minutes with a 5 minute postexposure evaluation
> period as was accomplished in the Halon 1301 portion of the study.
> Approximately 4.5 minutes into the exposure, the subject lost
> consciousness and both pulse and blood pressure dropped to zero."
>
> The test was aborted and medical personnel intervened and revived the
> subject.
> Suppose it wasnt a test in a medical lab, that person would be "dead".
>
> The industry, has in general, tried to "coverup" this "problem", often
> reporting "Human Subject Faints During Botched Air Force R-134a
> Inhalation test". They then go on to theorize that the nurse wiggled the
> blood drawing needle and that made the subject "faint". See (on the web)
> www.autofrost.com/humanhal2.pdf to download your own copy or call Monroe
> Air Tech at 1-800-424-3836 for a copy. Be your own judge. Using "0.4%"
> (4000 ppm) parts per million of R-134a vapor in air as the "lethal"
> amount, the following calculations were performed on several late model
> cars. They assume a bad evaporator leak or rupture, allowing the factory
> listed charge amount
>
> to escape into the passenger compartment. R-134a is heavier than air, so
> if the air is not "stirred" by a fan, heavier concentrations will be
> found in low spots and lower in high spots. For these purposes, we will
> assume the air is stirred and the concentration is uniform.
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Old 08-22-09, 06:18 PM   #12
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Quote:
Originally Posted by jhill20 View Post
Well I stopped reading after the original quoted message, but there alot more things to think about than oil getting back to the compressor...Each system is designed for a specific refrigerant. So, expansion valves, condensers, evaporators, and yes compressors are going to be different for each vehicle and each refrigerant. Yes the R.12 may carry oil back to the compressor, but assuming that year by year the r.12 charge will go down by a specified amount sounds spot on for an engineers "view of life". reality is you don't know how each system will react with both refrigerants. Most r.134a machines in use today already carry so much oil with their charge that there's no way you can guarantee no oil mixing. Plus no reputable technician will or should service an A/C system with using an identifier on it. And if the system is indeed contaminated...then they shouldn't touch it.

I am not discounting your personal experience, but what an engineer says "could" happen probably never does! trust me.

that's my 2 cents...
There are hundreds of blends out there just like freeze12, that is a mixture of 80% 134a and 20%142b. It can be legally purchased, once in the system it cannot be identified but is not considered as a contamination?!
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Old 08-22-09, 06:29 PM   #13
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Quote:
Originally Posted by roedel View Post
There are hundreds of blends out there just like freeze12, that is a mixture of 80% 134a and 20%142b. It can be legally purchased, once in the system it cannot be identified but is not considered as a contamination?!
yes it can senor. a good identifier will identify those. and they don't work very well, again the systems especially their individual components aren't designed for these frankensteined refrigerants. boiling points, operating pressures...all that stuff goes out the window. it's all changed. especially when demands are extreme such as here in phoenix Arizona where we have temps in excess of 100 for months on end. the systems really "enjoy" being operated correctly.

Although I must admit i don't have any experience "fussing" with anything you can by at say CSK or autozone....
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Old 08-22-09, 07:05 PM   #14
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Quote:
Originally Posted by jhill20 View Post
yes it can senor. a good identifier will identify those. and they don't work very well, again the systems especially their individual components aren't designed for these frankensteined refrigerants. boiling points, operating pressures...all that stuff goes out the window. it's all changed. especially when demands are extreme such as here in phoenix Arizona where we have temps in excess of 100 for months on end. the systems really "enjoy" being operated correctly.

Although I must admit i don't have any experience "fussing" with anything you can by at say CSK or autozone....
I can guarantee you, my R12/R134a blend worked much better than the original R12. And i read about many sucessfull conversions with that freeze12 stuff.

But to my humble oppinion nothing beats hydrocarbons same cooling less energy waste. People and industrie should avoid HFCs and switch to the enviromentally friendly and very efficient propane solution.

http://www.hydrocoolonline.com/technical.html
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Old 02-22-10, 06:21 AM   #15
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Hi
I was searching for anything to re-charge my R-123a So I found Something Maybe It Will Be More Useful For Your Issue And

otherwise it helps me too

Here
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Old 02-22-10, 06:21 AM
 
 
 
 
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