Frequently asked questions about R-12

(Freon (c)) and alternatives.

This version updated 6-19-96

This FAQ can now be found on the VetteNet home page,

Parts of this document are short, because I don't necessarily know the whole answer to the question.I will acknowledge up front that I view a lot of environmental regulation as extremely suspicious.That viewpoint probably comes across in this document.The point is, I welcome any comments about this document, pro or con, as long as they contain factual data. People who are long on opinion but short on fact need not bother writing to me. The EPA maintains a nice page listing the status of all refrigerants that have been submitted for use in mobile systems.So I am removing this information from the FAQ, as it was hard to keep updated anyway.

See their page at this site, the EPA also provides a classified ad service for speculators buying and selling R-12.The EPA notes that prices of R-12 have skyrocketed lately, they suppose that the following might be reasons:

o†† the end of production of R-12 on January 1, 1996.

o†† supplies being withheld for future years.

o†† lack of information preventing buyers from finding sellers.

o†† difficulties in moving existing stocks around the US.

What they forgot to include were the following:

o†† $5.45/lb federal tax on R-12 in 1995, increasing each year.

o†† Government bans always create high prices/black markets.


Please note that while I have tried to make this document as correct as possible, there are inevitably going to be some errors.Something that is legal today may very well not be legal tomorrow, and you are urged to call the EPA and your state to verify the legality of any A/C service you wish to perform.Some states have their own restrictions in addition to the EPA guidelines.The EPA has an ozone hotline (run at a profit by a private company, of course.)It can be reached at 1-800-296-1996.Sometimes they have the correct answers to questions.

Some procedures and products in this document may be illegal and/or dangerous depending on the context in which they are used.Specifically, replacing R-12 with an unapproved substance is illegal and can get you up to a $25,000 fine, with a $10,000 reward for whoever turns you in.Thatís nice, huh? This purpose of this document is expressly stated to be a source of facts.It is not intended in any way to encourage violating the law or other civil disobedience.

This FAQ is a source of facts on R-12, and other alternatives for mobile A/C systems.It is not a tutorial on automotive A/C service.Fixing your car's A/C is no more difficult and no more dangerous than changing plugs, replacing a distributor, or any other type of service that people typically do themselves to save money.You do, however, need to have the proper tools and knowledge to work on A/C.Purchase the factory service manual for your car.You will be better off for having spent the money.

Issues discussed within this document apply to the United States. Most R-12 using/producing countries have banned R-12 via the Montreal Protocol, but the substitutes discussed herein may or may not be legal for other countries.

Any opinions herein are mine, and although they are (or should be :-) widespread, they do not represent the opinions of anyone but myself.


Table of Contents:

1)What is R-406a (aka GHG Refrigerant 12 substitute)?

2)What is GHG-X4?

3)What is HC-12a?

4)What is OZ-12?

5)What is R-134a?

6)What is SUVA?

7)How does R-12 hurt the ozone layer?

8)It's a patent scam by DuPont!

9)What about flammability?

10) Who is MACS?

11) How do the EPA regulations affect the A/C D.I.Y. er?

12) Numbers and addresses of the players.

13) Where can I get more information about this stuff?

14) How can I make my own recovery equipment?

15) What is that white vapor coming out of the vent?

16) What is the two step upgrade?

17) How could I make an HC based replacement if I wanted to?

Appendix A:People

1)What is R-406a?


Newsflash:George Goble has filed for EPA approval on R-406a in mobile applications.Normally, it becomes legal to sell a refrigerant 90 days after application, even if there is no word on approval from the EPA.This is to encourage the EPA to act quickly since any refrigerant will be legal to sell by default after 90 days.The EPA has REVOKED this in the case of R-406a, since it is "weakly flammable" in the worst leakage case.In this case weakly flammable means that it can be ignited by a flame, but will not actually sustain a flame on it's own.It is self-extinguishing.

This rule was passed in July Ď95.George made his application in June Ď95, but the EPA is still applying the rule.This means that R-406a will have to successfully complete EPA approval before it will be legal to sell.You can voice you opinion on this to the EPA.The EPA web site is listed at the end of this document, and they have a feedback page for comments. EPA certification typically takes a year, so look for R-406a to be available in the summer of Ď96.

R-406a, formerly known as GHG R-12 substitute, is an ozone friendlier, R-12 compatible drop in refrigerant.It was invented by George Goble, who has a couple of patents on it.(, is a three part blend of 55% HCFC-22, 41% HCFC-142b, and 4% isobutene. It is compatible with the rubber seals and hoses, and with the mineral oils used in R-12 systems.In addition, it offers somewhat better performance than R-12.It is 95% less ozone depleting than R-12.(ODP of .05 vs. 1.0 for R-12).

R-406a was initially tested in August 1990 in three cars.By 1992, approximately 500 vehicles had this blend installed.Out of 500 cars, only one car suffered A/C system failure.Analysis showed that the Teflon piston rings had failed, which is a common failure mode for this particular compressor according to local mechanics.

R-406A may leak through "nitrile rubber" hoses, mostly found in foreign made cars, and port-of-entry add-on A/C systems.Most American cars, have used "barrier hoses" for years, and these work fine.All replacement hoses are of the "barrier" type now.

R-406a yielded a 4 to 13 degree F decrease in discharge air temperature over that of CFC-12 at ambient temperatures over 80 degrees F.Compressor discharge temperatures were also approximately 20 degrees F higher than comparable R-12 systems, but still low enough to prevent refrigerant or oil breakdown.

R-406a has been tested with CRYO-SILANE, a commercial A/C system sealant and was determined to be compatible.Cryo-Silane is effective at stopping leaks that fall into the three week to one year leak rate.

Since R-406a is a blend, a system should be evacuated before filling.The three components have different leak rates, so topping off would result in altered concentrations.In addition, R-406A (and all other blends) have to be charged as a LIQUID (yes, on the low-side, but bottle upside-down) because each substance has a different vapor pressure (thus different rate of release as a gas).But, you have to be careful to monitor the suction pressure and ensure that the flow from the can is gradual.If it gets above a certain point, you'll be sucking liquid and the compressor will fail.

This mix does contain Isobutene, which is required to disolve the mineral oil, but has been shown to be non-flammable in this blend, or weakly flammable in the worst case scenario.It has been classified as A1/A2 by ASHRAE.Topping off could result in higher concentrations of isobutene, which is why this practice should be avoided.Several things should be noted here, namely that _any_ refrigerant can be "flammable" if it contains dissolved oil and a rapid release occurs.The oil atomizes and can be ignited.In addition, any refrigerant that contains hydrogen atoms (HCFCs) can be flammable when mixed with large amounts of air under pressure.This includes R-406a, the EPA approved R-134a, R-22, etc.For this reason these refrigerants should not be mixed with air under pressure.

See the WWW page:

R-406a can be purchased from: Monroe Air Tech Bloomington, IN1-800-424-3836.



2)What is GHG-X4?


GHG-X4 is a reformulated version of R-406a. GHG-X4 is nonflammable as formulated, and does not become flammable after leaking and recharging (the refrigerant by itself).R-406a, upon which this blend is based, is classified as non-flammable in itís original blend, and weakly flammable after the worst case leakage.

Under the 1990 Clean Air Act as amended, GHG-X4 is legal to sell in the US for automotive and stationary A/C and refrigeration systems starting Jan 17, 1996.Under the EPA SNAP process, GHG-X4 will be evaluated and either listed as "acceptable" or "unacceptable" for various end uses.If declared "unacceptable", then sale must stop.If declared "acceptable", it may be continued to be sold, but probably with "restrictions" attached, like unique threaded fittings which go onto cars, and never come off, pressure cutout switches, etc..

GHG-X4 is made from the following components and weight percentages:

R-600a†††††††††† 4%(R-600a is isobutene - carries oil)

R-142b†††††††††††† 16.5%

R-124†††††††††††††† 28.5

R-22†††††††††††††† 51%

GHG-X4 works with mineral or AB oils found in R-12 systems, no retrofit needed.However, old "nitrile" rubber hoses should be changed to the newer "barrier" (nylon lined) hoses as R-12 and GHG-X4 leak faster thru nitrile hoses.Most American cars have used barrier hoses for years, so no change is needed.Do not use with "PAG" or "POE" oils (R-134a systems). Many times it will work in R-500 systems unmodified, TXV systems might need a new "power-head" on the TXV. R-500 cap tube systems should be ok.We have even had customers (with R-406A) "retrofit" R-502 systems (refrig transport) to R-406A which is very similar to GHG-X4 by only changing the expansion valve.. This should not work, but we have several customers who swear on a stack of Bibles that it works.I would expect only 50% of original R-502 capacity.

Cooling performance is equal to or better than R-12. (similar to R-406A)GHG-X4 was unveiled Jan 18, 1996 at the MACS meeting/show (Mobile Air Conditioning Society) booth 106 in Orlando, FL.

Call 1-800-424-3836 (Monroe Air Tech) or 1-800-669-5730 (McMullen Oil Products) or see the WWW page.The WWW page has a more extensive GHG-X4 FAQ.Available in 25 lb cylinders (equiv to 30 lbs of R-12) or in 9.6 oz cans (equiv to 12oz R-12). Contains EPA class II substances (HCFCs), and must be recovered and not vented to the atmosphere.Currently marketed under the name "AutoFrost" and "Chillit".



3)What is HC-12a?


HC-12a is manufactured by OZ Technology as a direct R-12 and R-134a replacement requiring no retrofit.It is a second generation product that replaces OZ-12.It is a patented hydrocarbon blend of unknown composition.It has 0 ODP and 8 GWP.It is compatible with any system containing R-12 or R-134a, including both mineral and synthetic oils, rubbers, metals, etc.It is up to 30% more efficient than R-12, which reduces load on the compressor and engine.Since it is a hydrocarbon blend, it is flammable.It has had a strong odor added to help identify leaking systems.DOE studies have shown that the risk of HC based refrigerants in mobile A/C units is negligible.

The EPA banned it for use in mobile applications on June 2, 1995.The ban will take effect 30 days after publication in the Federal Register, which should be mid-July 1995.Approval was removed due to flammability concerns.OZ technology has not done a risk assessment to determine if there is a flammability hazard.


4)What is OZ-12?


OZ-12 was the first-generation R-12 replacement from OZ Technology. It is a hydrocarbon based refrigerant of unknown composition.It has been supplanted by HC-12a.It has been banned by the EPA for over a year due to flammability concerns.

Report EA94-006 from DOT Auto safety hotline


5)What is R-134a?


R-134a is the current replacement for R-12.Most new cars manufactured now have R-134a in their air conditioning systems, and all manufacturers plan to move solely to R-134a by the end of 1995.It is a retrofit rather than a replacement, as it requires some parts to be replaced before it can be placed into an R-12 system.R-134a is not compatible with the mineral oil used in R-12 systems, and uses a PAG (polyalkylene glycol) based oil instead.This oil is not compatible with the rubbers typically used in an R-12 system, so at a minimum all O rings and hoses must be replaced.In addition, R-134a has 20-30% less cooling capacity than R-12.Newer systems are designed with this in mind, but older systems just will not provide as much cooling capacity if they are converted to R-134a.In addition, R-134a will react with the aluminum chlorides left behind fron R-12 and form acids that eat at system components.These chlorides form on the surface of aluminum parts that are exposed to R-12.

There are other problems with the oils used with R-134a.PAG oils may be destroyed from residual aluminum chloride coating the insides of pipes, etc, left over from when R-12 was in the system.These chlorides cannot be flushed out and are not present in "new cars"."Ester oils" (POE) are more tolerant of the chlorides, but are still 10X more moisture sensitive than R-12 mineral oil.PAG oil is about 100X more moisture sensitive. Ester oils have less lubricity than PAG oils.

R-134a is flammable when mixed with air and placed under pressure, as are all HFC refrigerants, including R-406a, R-22, and others.PAG based oils are skin irritants and require impervious gloves to be worn when handling.R-134a can irritate the eyes, nose and throat.Exposure to R-134a has been shown to cause benign tumors in lab animals, under the non-realistic conditions of 5% atmospheric content over 2 years.Contrast this with R-12 and mineral oil, which are known safe under all conditions.

R-134a currently does not require a license to purchase, but the EPA is considering requiring one.The initial rule will be published in August 1995.90 days of public comment will be accepted, then the final rule will be published in November 1995.


6)What is SUVA?


"SUVA" is DuPont's name for the family of new refrigerants.Seems that "Freon" (their current family of refrigerants) has a bad stigma attached to it now (Ozone layer). HFC-134a has a new "Suva" designation as well.

DuPont has also announced SUVA MP-36 and -39 which are "almost drop-ins"for R-12 in automotive A/C. They are blends of R-22/R-152a/R-124 which closely simulate the temp/pressure curve of R-12.I have heard that one will need to change out the oil (need to use alkyl-benzene oil instead of mineral oil) and to use a new drier with XH-9 desiccant instead of the standard XH-5 desiccant (the R-152a attacks XH-5).

SUVA is also the capitol of Fiji.


7)How does R-12 hurt the ozone layer?


There are different wavelengths of UV called UVC and UVB.UVC is higher in energy (shorter wavelength) than UVB.Oxygen absorbs UVC, and ozone absorbs UVB.It is true that normal molecular oxygen absorbs UVC, and it is also true that it's not likely that UVC levels will climb because of ozone depletion.

Current theory holds that chloral-fluorocarbons (CFCs), once released, work their way into the upper atmosphere (stratosphere), where the chlorine atom is stripped from the CFC by the ultraviolet light.The chlorine atom then reacts with the naturally occurring ozone and changes it into normal oxygen.The chlorine is a catalyst in this reaction, which means that it enables the reaction to take place, without actually being used in the reaction.The chemical reactionsthat form and deplete the ozone are:

Ozone forming (good)

(1)O2 + UVC -> O + O†† †††††† (UV is ultraviolet light)

(2)O2 + O -> O3

Ozone depleting (good)

(1)O3 + UVB -> O2 + O†††††† (This reaction protects us from UVB)

Ozone depleting (bad)

(1)Cl + O3 -> ClO + O2

(2)ClO + O -> O2 + Cl

Notice that after both the depletion reactions occur, the chlorine atom that started the whole thing is still hanging around to cause problems.This is why the CFCs are bad for the ozone.The chlorines cause the ozone to be destroyed, but aren't used up in the process.

Other references on ozone are:

Description of how chlorine affects the stratosphere

Greenpeace Ozone crisis page

There is a very good FAQ on ozone depletion posted periodically to news answers.It is very readable and provides much more information than I have provided here.It is also available online at:

Ozone Depletion Thematic Guide" produced by CIESIN:

"US EPA Stratospheric Ozone Home Page"


8)It's a patent scam by DuPont!


No it's not.R-12 was invented in the 1930s.The patent is long gone.


9)What about flammability?


Most of the proposed drop-in alternatives for R-12 contain flammable materials.In November of 1991, the DOE commissioned a preliminary study of the risks involved.The conclusion of the report is that the risk of fire and/or explosion is very remote.The full text if available from NTIS.I quote relevant portions of the document below:

"Non-inert Refrigerant Study for Automotive applications "Prepared for US Dept of Energy by Arthur D Little, John Dieckmann, Jeffrey Bentley Page 36

"The event of most concern involve a rapid release of refrigerant into the engine or occupant compartment.Vehicle crashes are the only likely source of a significant number of accidental releases."

"The risk of injury from leaks into the occupant compartment is likely to be very small with current designes because

1)the interior A/C components are robust and well isolated from front/side crashes;

2) no credible ignition sources were found _inside_ the occupant compartment;

3) window blowout is predicted to occur before explosive overpressures reach the level required for injury; and 4) the thermal pulse from an explosive event would have insufficient energy to cause life threatening injuries.With a conventional A/C system, the risk of refrigerant release and ignition in the occupant compartment appears to be very small, approximately 3x10^7 such incidents per automobile, per year.With approximately 140 million passenger vehicles in service, approximately 40 incidents per year would occur if no A/C system design changes were made.As discussed in section 6.3, we believe that this estimate may overstate the risk considerably, as no evidence was developed that indicates that evaporators and connecting lines within the passenger compartment are damaged to the point of leakage in even the most severe collisions."

"For engine compartment leaks in an A/C system of conventional design we estimate:

- Engine refrigerant leakage will occur in a significant number (17%) of "tow away accidents."

- Jet mixing and dispersion will limit the probability of formation of a flammable mixture in the vicinity of an ignition source.

- Only high energy ignition sources (broken battery cables, overheated catalyst jacket) are likely to cause ignition

- Explosive overpressures in the engine compartment will be limited below levels of concern (<<1 psi) due to venting out the bottom of the engine compartment.

- Conventional systems will have an incidence of fire on the order of 14 to 50 per million vehicles resulting primarily from ignition of refrigerant while it is leaking."

"With relatively minor redesign we estimate the annual incidence of engine compartment fire will be reduced to less that one fire per million cars."

The authors do CYA by stating that the study is preliminary and more in-depth research is needed before flammable refrigerants become widespread.


10)Who is MACS?


MACS is the group mostly responsible for the current state of affairs in mobile A/C.MACS stands for Mobile Air Conditioning Society.They are the group that petitioned the EPA to outlaw alternatives, in spite of the fact that the EPA admitted that there was no environmental reason to ban the alternatives.As if that wasn't enough, you now have to pay MACS for the privilege of buying the freon and alternatives that they were so successful at driving the price of up.Note that you need a license to purchase any sort of refrigerant these days.Here's how to get the your very own federal license to purchase refrigerants:

1:Send $20 to MACS.

2:In a couple days you'll get a test and study materials in the mail.Read the study guide (27 pages), take the test at your leisure (it's open book, but you can't get help from anyone else.)

3:Send the test back in.If you answered 21 of the 25 questions correctly, then you are smart enough to buy refrigerants and they will send you a license in 4-6 weeks.

This test only covers EPA regulations.It is not intended to teach you anything about A/C systems.Duh, that makes sense.

There are other companies as well, but I do not have any information on them.


11)How do the EPA regulations affect the A/C D.I.Y. er?


The short answer is:Other than the need for an easily obtained license, and the 900% increase in the price of R-12, there is very little impact on the D.I.Y. er."Topping off" known leaking systems is perfectly legal, although it is logically inconsistent with the EPAís stated purpose.

First, there has been some comment on the "service for consideration" loophole. This clause is only in, and only applies to, Section 609 of the Clean Air Act.Section 609 deals with the various certifications needed by technicians and the equipment they use.This "loophole" simply states that anyone providing A/C service for free does not have to meet the certification requirements set forth in section 609.This means that D.I.Y. ers do not have to be certified technicians, and do not have to use approved equipment for refrigerant extraction.D.I.Y. ers must use extraction equipment, but it can be a home-built system.Specifically, this clause does not apply to alternative refrigerants.It is illegal to use anything except approved refrigerants as a replacement for R-12.Please note that the EPA only regulates replacements for R-12.There are no restrictions on what may be introduced into an R-134a system, or what may be introduced into a system that has been converted to R-134a.

The ban on venting refrigerants with a non-zero ODP still stands and applies to everyone.Starting in November 1995, no replacement for class I or class II refrigerants can be vented.This will include hydrocarbon based replacements if they ever achieve permanent approval.What if these HC based replacements are vented from a grill?It's unclear what the penalties will be for a person whose torch fails to light on the first spark.

The ban on non-approved alternatives still stands, and applies to everyone.Only alternatives listed by the EPAís SNAP (significant new alternatives program) may be used in cooling systems.

This section used to maintain a list of available alternatives and their status, but there are too many to keep up with now.The EPA has a very nice HTML formatted document that shows all substitutes and their current status.Please see this WWW page at

The bottom line is that D.I.Y. ers can continue to service their air conditioners with only minor additional headaches (other than the 800% increase in the cost of R-12, courtesy of the US government).First, you have to take the MACS test (or equivalent) to get the federal license to purchase refrigerants.Second, you must have recovery equipment.This does not have to be certified equipment.The only requirements are:"the equipment must not vent to the atmosphere, and it must be capable of pulling at least 104mm of vacuum."[Jeffrey Levy] All refrigerant must be recovered from the system returned for reclaiming.Recovered refrigerants must be stored in a DOT approved container, marked 4BW or 4BA.The cylinders used by propane grills and on campers meet this specification.


12)Numbers and addresses of the players


EPA Ozone hotline:1-800-296-1996


PO Box 97 East Greenville, PA, 18041 (800) 609-6227 (215) 679-2229 (215) 541-4635 (fax)

OZ Technology 1 208 664-6196

Monroe Air Tech (R-406A) 1 800 424-3836

Socity of Automotive Engineers (SAE) 1 412 776-4841

Greenpeace ozone crisis page

NTIS, National Technical Information Service US Dept of Commerce Springfield, VA 22161 (703) 487 4650

Cryo-Chem Intl.(makers of Cryo-Silane)1-800-237-4001

Intermagnetics (FRIGC) 1 800 555 1442


13) Where can I get more infomation about this stuff?


Here are references for material about the information in this FAQ.I have not read/looked at all of these.I make to claims as to their factual validity.

Trashing the Planet : How Science Can Help Us Deal With Acid Rain,†† Depletion of the Ozone, and Nuclear Waste (Among Other Things) by Dixie Lee Ray , Lou Guzzo Published by Harperperennial Library Publication date: May 1, 1992

The Holes in the Ozone Scare : The Scientific Evidence That the Sky Isn't Falling by Rogelio A. Maduro , Ralf Schauerhammer Published by Twenty First Century Science Publication date: July 1992 ISBN: 0962813400

"Atmospheric ozone" brief description of how ozone depletion occurs.

"US EPA Stratospheric Ozone Home Page"

"Usenet FAQ on ozone depletion" is a FAQ that exhaustively covers questions and answers on ozone depletion.It is also posted regularly to news answers

"Government Publications Online" Electronically searchable index of government publications.Searches may be performed on House and Senate bills, the Federal Register, US Code, etc.

"Ozone crisis page" WWW page sponsored by Greenpeace about ozone depletion.


14) How can I make my own recovery equipment?


Some easy ways to recover refrigerant are to take a recovery cylinder (or even a propane BBQ grill tank - it is DOT legal) and pull a vacuum on it just before the first use.

A "50lb" recovery cyl is the same size as the 20lb propane BBQ grill tank.For these purposes, a 30lb recovery cylinder would work better (donít use a DOT39 "throw away" refrigerant cylinder).Get a Rubbermaid

5 gallon water cooler, and stick the 30lb cylinder in it, and add dry ice around the edges.This cools the cylinder so both R-12 and R-22 can be removed, and it will draw a vacuum on the system if left on long enough. If you can get it, liquid nitrogen works nicely also (-312F).Both dry ice and liquid nitrogen are very cold and can cause frostbite burns.Be careful.

Pre-cooling a cylinder in a freezer is usually not sufficient, it has to be colder than -21F to extract a charge from an R-12 system down to 0 PSIG.The cylinder will warm up as the charge is removed.

Wrapping a recovery cylinder with slightly flattened 3/8" copper tubing (on the outside), slowly venting liquid CO2 through the tubing would also be cold enough.

Be very careful not to "overfill" the cylinder, use scales and don't exceed 70% of the "water capacity" (marked as WC), typically a BBQ grill tank will be WC 47.7, subtract out the tare weight (listed as TW), typically 12-13 lbs on a BBQ grill tank.JC Whitney sells propane level gauges which are temp strips which stick on the side of the tank, pour hot water on it, and the liquid level becomes visible.

If the cylinder is overfilled, thermal expansion may result in 100% liquid full, when the cylinder warms up, causing the safety (popoff) to vent or the cylinder to explode.--ghg

You can also build a recovery system out of an old fridge or electric A/C compressor.I removed the compressor from a 4 ft^3 (dorm style) refrigerator.The fridge was given to me as it no longer cooled.The compressor relay was bad, but the compressor itself was perfectly good.$10 worth of brass fittings and some teflon tape from the hardware store enabled me to connect a line from the gague set to the compressor intake.Running this compressor for approximately 30 mins drew over 30Ē of vacuum.Another set of fittings allows the compression side to be connected to a BBQ grill tank, thus resulting in a DIY evacuation system that is perfectly legal for DIY (unpaid) use.Pull a vacuum on the BBQ tank first.

Note that the fridge compressor got very hot during use, hot enough to burn skin.I suspect itís not designed to run for half an hour at a time.Next time I will place a fan blowing on it.A compressor from a house or window A/C unit would be a better choice as a vacuum pump, but the price was right for this one.--author


15) What is that white vapor coming out of the vent?


Water vapor.You can see this any time the relative humidity is high outside and the A/C is not on "recirculate".It's not freon, or plutonium, or anything else.


16) What is the two step upgrade


Here in Texas, thatís what we call a waltz...

Ba dum bump.

All hilarity aside, section 612 of the Clean Air Act gives the EPA a mandate for regulating Class I and II refrigerants, and replacements for them.The EPA does not regulate other refrigerants, or replacements for non-Class I or II refrigerants.In other words, the ban on HC based or other refrigerants is only in the context of using them to replace R-12.While it is illegal to replace R-12 with HC-12a (for example), it is not illegal to replace R-134a with HC-12a.A two step upgrade can be done to convert an existing R-12 system to the refrigerant of your choice.First convert the system from R-12 to R-134a, or another EPA approved non-class I or II substitute for R-12.Since the EPA doesnít regulate your substitute, you can leave it in there or convert to any other refrigerant of your choice.You are free from all the other EPA regulations, such as the type of fitting, etc.It is left as an exercise to collapse this process to the minimal number or steps required to achieve the final objective, using a non-EPA approved R-12 substitute.The EPA has stated that they will vigorously prosecute anyone they suspect of performing a "sham switch".So try the replacement for a while, and if it doesnít perform to your satisfaction feel free to replace it.

17) How could I make an HC based replacement if I wanted to?


So youíve done the first step of the two step upgrade, at least in theory, and now you are ready to upgrade to an HC based refrigerant for better performance.But you donít want to send a lot of money to OZ technology, or you canít find them.This section is for you.It describes how you can make your own refrigerant from commonly available hydrocarbons.The procedures described in this section were taken from rec. auto. tech archives, dating from June 1991 to the present.Most of the text can be attributed to either George Goble or John DeArmond.


†††††††††††††††††††††††††††††† Disclaimer

Some of the procedures described in this section may not be legal.

Refilling some types of pressurized containers is illegal, as is replacing R-12 directly with a non EPA approved substitute.

Several states have banned flammable refrigerants outright.The current list is:Arkansas, Conn., Idaho, Indiana, Kansas, Louisiana, Maryland, North Dakota, Oklahoma, Texas, Utah, Virginia, Washington , DC.

Check with your state to see what the exact restrictions are, if any.

Hydrocarbons weight much less than CFCs, consequently much less mass is required to achieve the same pressures.Always charge using gauges to prevent overfilling.Check the pressure and temperature of your blend if you pre-mix and store.The pressure should be the same as R-12 at the same temperatures.Adding propane will increase the pressure at a given temperature, adding iso-butane will reduce it.


The most commonly asked about hydrocarbon mix is 21% isobutane, 79% propane, by weight.Note that is isobutane, not butane or n-butane.This mix has the same temperatures and pressures as R-12, but performs better in your A/C system, partially due to being a blend.Hydrocarbons weigh less than CFCs, so you will need about half the weight of hydrocarbons to achieve the same performance.The paragraphs below describe how to charge this mix directly into your A/C system from the can, and how to pre-mix it in a large container for future use.Be sure to charge with gauges so you can stop at the appropriate pressure.Do not add the same weight as you would if it were R-12.

Side tappers are available from JC Whitney and other places.A side tapper is a device that taps a can by piercing the side of the can, rather than the top.It will work on the small cans of refrigerants as well as cans containing other substances, whereas the standard A/C tapper will only work on refrigerant cans.In a ruling from the summer of 1995, the EPA ruled that it is illegal to use side tappers on cans of approved refrigerants.Use them on R-12, or on your custom blend, but itís illegal to use them on R-134a or any other approved R-12 substitute.Youíre supposed to use the fitting on top of the can.



Isobutene is available as the fuel used in Gaz brand camping stoves.Read the label to make sure you are getting isobutene and not n-butane.isobutene is generally used in stoves designed for low temperature use.Gaz sells both plus a propane/butane mix so read the label.Propane is conveniently available in propane torch cylinders.The odorant does not harm its use as a refrigerant.Don't use gas grill propane.This stuff is generally fairly wet.



Youíll need two old torch bodies fitted with refrigeration flare fittings, an empty propane torch cylinder, a side tapper, and some standard refrigeration service hose.

An empty propane torch cylinder makes a very good mixing container, particularly the large fat ones.An old torch valve fitted with a refrigeration flare fitting lets you use it with A/C equipment.The procedure is simple and requires only a scales of some sort.A postage scale will work fine.Evacuate the propane cylinder if you have a vacuum pump.Then using a side tapper for blow-off cans (the type that punches a hole in the side of the can), introduce the correct weight of isobutane from the Gaz cylinder.Then top the cylinder off with the required weight of propane from another propane torch cylinder.Warming the donor cylinder will drive the process.A second torch body fitted with a refrigeration flare will let you hook the two cylinders together with a refrigeration service hose.Be sure not to overfill the recipient cylinder.Check this by slightly lifting the safety valve with the cylinder sitting upright.If liquid comes out (white mist, real cold), bleed the cylinder until the liquid is below the bottom of the safety valve.Needless to say, do all this outside.

Before using the mix, double check the accuracy of the blend by comparing the vapor pressure in the cylinder to its temperature.This is easily done using refrigeration gauges.The vapor pressure should agree with that of R-12 +- 10 psi or so.When using your mix, charge with the bottle upside down, ie liquid into the system.Otherwise the propane will charge first due to itís higher pressure.Charging as a liquid ensures that both the propane and isobutene charge according to their proportions.Be careful to charge slowly, however, because if the liquid gets back to the compressor it can destroy it.

When you modify a torch body, you'll need to find and drill out all restrictions that limit the propane flow to the torch.Typically there is a restriction and/or a check valve in the barb that taps the cylinder and another one downstream of the control valve.

BTW, propane torch cylinders make convenient replacements for blow-off cans.They are much more gas-tight than the typical disposable Freon cylinder so transferring valuable R-12, GHG-12 or whatnot makes real good sense.And they are more reliable.Instant sickness is dropping a 30 lb can of Freon onto something that punctures it. :-(Be sure to label the cylinder contents.

It is illegal to refill and transport disposable containers.BBQ grill containers are legal to refill, but are much less convenient.Be sure whatever container you use is clean initially.



Go get a 6oz can of "isobutene" camping fuel.Charge that into the evacuated system first.Next follow up with 16 oz of propane (you will have to crock up a fitting to mate with a 16 oz torch tank).That should be close to correct blend and amount of charge to run a typical car A/C.It will be slightly lower in capacity then R-12.This mix will be 27% isobutane, 73% and will cause lower pressures than R-12, but should be close enough to work.The best mixture is 21% isobutene, 79% propane, so adding less isobutene and more propane will help.When it is time to recharge again, vent the remaining charge, and start over with a new fresh charge as the isobutene and propane will leak at different rates.



You can clean the tanks by removing the valve, inverting them and blowing them out with 1,1,1-trichloroethane with an automotive power sprayer (like used for degreasing engines and about 200 PSIG air pressure.Next, install the valves, and pump them down to 400 microns of vacuum (an hour or so), and fill them with dry nitrogen for storage.

On a propane tank, DO NOT USE WATER. K-Mart "brake cleaner" is 111-trichloroethane/perchlorethylene which would work fine.AN easier way, may be to just get it filled with propane, and invert the tank (in some field away from fire, sparks, (unless you want to participate in rec. pyrotechnics)), and open the valve all the way, and shake the tank.This should blow the shit/crud out. 5 or 6 seconds should get most of it.