Using Duracool and other Hydrocarbon refrigerants

PLEASE NOTE: I AM NOT AN EXPERT ON AUTOMOTIVE REFRIGERANTS. THIS SUBJECT MATTER HAS NOT BEEN REVIEWED BY ANY EXPERTS AND IS PROVIDED FOR EDUCATIONAL PURPOSES ONLY AND MAY CONTAIN ERRORS. USE AT YOUR OWN RISK ! WARNING: HYDROCARBON BASED REFRIGERANTS SUCH AS: Duracool®-12A (TM) , RED-TEK
12A (TM) , Enviro-Safe (TM) , Frosty Kool (TM) AND OTHERS ARE FLAMMABLE AND MAY BE ILLEGAL FOR YOU TO USE FOR YOUR INTENDED USE IN YOUR STATE.

https://forum.ih8mud.com/threads/duracool-12a-tm-envirosafe-tm-redtek-tm-frostycool-tm-aka- hydrocarbon-ac-refrigerants.1048595/

Recently I decided to do some AC work on my 85 FJ60 and wanted to get it done before it starts getting too warm here in Las Vegas. The purpose of this write up is not so much about the AC repairs but the choice of refrigerant I chose and why. You Have been warned. This is a Nerd Alert….. there is talk of flammable and toxic gases, of testicular cancer, and frostbitten skin.. along with a bit of science ahead in this post. So if you are easily bored.. move on to the Rig Pics and Eye Candy.

Hydrocarbon Refrigerants have many performance and environmental advantages over synthetic, especially in R12 applications. They are gaining in popularity even among Domestic USA appliances where up to 150g charges are now allowed.

If you stick around It is my hope that this post can serve as a summary of the many sources and peer reviewed publications, I have found so that the reader may make their own conclusions as to whether or the safety and efficacy of a hydrocarbon refrigerant is right for you to use in your vehicle application and even your home refrigerator or wine cooler.

This is a long post. If you want to get to the good parts, read the Review of MVAC Refrigerants and Their Characteristics, Flammability and Explosion Risk, and DURACOOL CHARGING INSTRUCTIONS FOR MVAC APPLICATIONS

I try to acclimate myself to the 110F plus heat we get in the summer here in Southern Nevada but at times you need more than just the windows down to cool off. Having a working AC system can be critically important for safety here. Since converting my AC system to R134 I was really not pleased with the cooling performance. I could tell the compressor was working harder due to higher head pressure required to get R134 to cool. In the thin summer air my poor 2F motor has to work really hard to get my heavy Expo-build up the hills and passes here and running the AC at the same time was out of the question.

Recently, I had a rock strike my front condenser and a slow leak developed. By the time I noticed it all the refrigerant had leaked out. I ordered a new Denso condenser and drier and a Sanden gasket kit. While I was waiting for parts to arrive I started researching which refrigerant to use. I was not keen on going back to R134 and some shops can still charge up R12 if you want to pay the price. However, it is performance I am after and I really did not want to flush out all compressor oil from the system again in order to go back to R12 and Mineral Oil. I decided on DURACOOL® 12a which is a hydrocarbon based refrigerant.

We have all heard about “Drop In Replacements” for R134A and R12 retrofitted systems. Most of them are hydrocarbon blends of purified propane ( R290 ) and isobutane ( R600A ) which can be used in refrigeration and AC systems designed for R-12 and R134a. Commonly referred to as 12a hydrocarbon refrigerant it provides better cooling than an R-12 system retrofitted to R-134a, with much greater energy efficiency as well. Unlike R-134a, 12a hydrocarbon refrigerant is completely compatible with the gaskets, hoses and oils used in most R-12 systems which use barrier hoses. Head pressure ( the high side of the compressor ) is typically lower that R12 and R134a and typically only 35% of the original refrigerant charge is required to charge they system. The blend is also classified by the EPA as an A3 / H220 flammable refrigerant. However with the necessary treatment I believe ( and studies have shown ) that risks can be mitigated to a very acceptable level in their use. This category of hydrocarbon refrigerants are generally referred to “Natural Refrigerants” becoming more commonplace. At the time of this writing the EPA is allowing refrigerant charges of up to 150g in domestic refrigerators in the USA. Hydrocarbon refrigerants are here to stay so if you are worried about flammability please read on. ( FYI: That can of Glade air Freshener in your bathroom has 113g of R290 propane as a propellant)

This current push is largely due to the fact that natural refrigerants have a zero impact on the Ozone Layer, minimal impact with respect to global warming and are now permitted by the EPA to be vented into the atmosphere instead of recovered during service. In the 1990’s the EPA issued rulings on the use of 12a hydrocarbon refrigerant in MVAC applications that were not favorable which were largely due to flammability concerns. Those rules still stand today despite the EPA approval of a new refrigerant called R1234-YF and R-1234ze which are classified as mildly flammable. The 12a hydrocarbon refrigerant cannot be patented as it is a natural product and the other refrigerants such as R1234-YF has backing of the large chemical companies. If you ask me.. something does not pass the smell test on this.

The rest of this write up will consist of studies and citations on hydrocarbon refrigerants as it applies to Motor Vehicle Air Conditioning (MVAC) applications. Where possible I will provide url links but also citations, as links tend to move around or get broken over time.

Review of MVAC Refrigerants And Their Characteristics:

R12 or Dichlorodifluoromethane is a colorless gas usually sold under the brand name Freon®. (Freon® which is a common catchall phase for refrigerant which is actually trademarked by DuPont) and a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant. It is largely non-toxic to humans and is non-flammable but very harmful to the Ozone Layer. Typically, when used in MVAC applications R12 is combined with Mineral Oil to lubricate the compressor. If an MVAC system is catastrophically decompressed in an accident or component failure the atomized mineral oil becomes very flammable.

The MSDS from National Refrigerants lists the Auto Ignition Temperature “Not Known”. Note: When exposed to sunlight or heat R-12 decomposes. One of the byproducts of this is highly toxic Phosgene Gas ( Mustard Gas ) R-12 is still available for purchase with a 609 EPA certification but no longer produced in the United States due to EPA regulations as it was banned by the Montreal Protocol in late 1993

R134 or 1,1,1,2-Tetrafluoroethane also known as norflurane, R-134a, 134a, Forane 134a, Genetron 134a, Florasol 134a, Suva 134a, or HFC-134a is haloalkane refrigerant a with thermodynamic properties similar to R-12 (dichlorodifluoromethane) but with insignificant ozone depletion potential and medium global warming potential. It is generally considered to be non-flammable but shares the same flammability issues with the PAG Oil or Ester Oil lubricant used for the compressor during a catastrophic decompression. Auto Ignition Temp is 1328°F. It is also considered a testicular carcinogen. It is rumored that EPA plans a phase out to R1234-YF by encouraging the manufacturers to increase the price. As of January 2018 the EPA is requiring a 609 certification to purchase large cylinders of product. The availability of small cans for the general public remains the same at this time however the cans must have self-sealing valves.

ELF ATOCHEM NORTH AMERICA INC (One of the larger producers of R-134a) states in their MSDS the following “Respiratory Protection (for discharge of R-134a) IN INADEQUATELY VENTILATED AREAS, A NIOSH/MSHA APPROVED (TC-18C) SUPPLIED AIR RESPIRATOR/SCBA IS REQUIRED. Ventilation: CHECK AIR FOR CONTAMINANT & FOR OXYGEN DEFICIENCY. USE LOCAL EXHAUST SYSTEM IF VENTILATION IS INADEQUATE. Protective Gloves: SYNTHETIC RUBBER/NEOPRENE Eye Protection: GOGGLES Other Protective Equipment: LIQUID GLOVES ARE RECOMMENDED FOR PROTECTION FROM COLD. Work Hygienic Practices: REMOVE/LAUNDER CONTAMINATED CLOTHING BEFORE REUSE. DESTROY CONTAMINATED SHOES.” A later safety bulletin revises this for well ventilated areas as well !

R1234-YF or 2,3,3,3-Tetrafluoropropene, is a hydrofluoroolefin (HFO) with the formula CH2=CFCF3. This colorless gas has been approved as a replacement for R-134a as a refrigerant in MVAC applications. Most all automotive manufacturers are switching to R1234YF as of the 2017/2018 Model year. R1234-YF has been classified as H220: Extremely Flammable in the MSDS from National Refrigerants. However ASHARE ( American Society of Heating and Air-Conditioning Engineers ) states it is mildly flammable with an A2 designation. When combined with compressor oil under pressure it becomes extremely flammable during a catastrophic decompression.
In the atmosphere, HFO-1234yf degrades to trifluoroacetic acid, which is a mildly phytotoxic strong organic acid with no known biodegradation mechanism in water. In case of fire it releases highly corrosive and toxic hydrogen fluoride and the highly toxic gas carbonyl fluoride.

12a HYDROCARBON REFRIGERANT (12a) is a mixture of hydrocarbons specifically purified propane (R- 290) and isobutane (R-600a), and is therefore considered nearly non-ozone-depleting when compared to R-12 or R-134a. The mixture can be used in refrigeration systems designed for R-12 and R-123a. 12a provides better cooling than an R-12 system retrofitted to R-134a, with much greater energy efficiency as well. Unlike R-134a, 12a is completely compatible with the hoses ( NOT TO BE USED WITH RUBBER HOSES FOUND IN THE 1960 MODEL YEARS ) and oils used in R-12 systems and seals, making the conversion much easier to accomplish. 12a is also patent-free due to its non-synthetic nature. Common trade names include: Duracool®-12A, RED-TEK 12A, Enviro-Safe, Frosty Kool and others. The difference between the products is mostly the R-290 to R-600 ratio, the addition of a Mercaptan ( sulphur or pine ) smell for leak detection and the use of lubricant some also have UV dye added. 12A has an auto-ignition temperature of 1635°F and is categorized as an A3 and H220 Extremely Flammable rating which is the same category for R1234-YF according to the MSDS from National Refrigerants. In practice, the required weight of 12a needed to give the same refrigeration capacity and performance as R12 or R134a, is between 35% and 40% of the original system charge by weight. Significantly less product use by weight than either traditional products alone lessens the flammability risk in MVAC applications. The 12A Molecule approaches three times the size of R-134a which makes it less prone to leak as does the fact that 12a operates at lower pressures. Also both propane (R-290) and isobutane (R-600a) are used as aerosol propellants in many products.

The EPA considers the 12A category of refrigerants as a second generation, non-ozone depleting replacement for R-134a and all other non-ozone depleting R-12 substitutes. The EPA’s Final Rule, issued April 1, 1994, states: “In this final rule, the agency has determined that second generation replacements, if they are non-ozone depleting and are replacing non-ozone depleting first generation alternatives, are exempt from reporting requirements under Section 612”. They are not a direct replacement for R-12 and can only be legally used in systems that already use or have been converted to R-134a. Also several states have prohibited the use of flammable 12a refrigerants Including Arizona, Florida, Idaho, Louisiana, North Dakota, Oklahoma. But they allow the new flammable R1234YF refrigerants However I have found no mention of those states prohibiting them in domestic and commercial refrigeration applications. The EPA ruling on prohibiting 12A in applications that used R-12 (Prior to conversion to R-134a) makes no sense to me other than a bureaucratic play to quell the public’s impulse to use them in the early 1990’s when R12 was being phased out. The regulations to me, make no sense at all technically but that is my view not the EPA’s

In summary all refrigerants are flammable to some degree especially when mixed with their respective compressor oil and released as a mist under a catastrophic decompression. Also know that when handling ALL these refrigerants there is a risk of frostbite if it should get on your skin in the liquid state. So yeah… all this stuff is nasty to some degree in a MVAC application. Your skin can get frozen, your nuts can get cancer and fall off, you can get burned by flames or hydrogen fluoride and inhale lovely phosgene or carbonyl fluoride gas. One must use the proper personal protect gear like gloves and safety glasses when handling, and use safety precautions like no smoking or open flames when working on MVAC systems. Lest we forget.. There are other flammable liquids under your hood as well like gasoline, brake fluid, power steering, ATF fluid, gear oil, and even the antifreeze.

Practical Safety Studies

There are roughly 10 – 20 million vehicles that are using 12a worldwide. Mostly in Asia, Europe, the US and Australia. If there was a serious problem with hydrocarbon refrigerants you would know about it by now. There a few notable papers written about them in the 1990’s demonstrate that under the normal circumstances found in an MVAC application the margin of safety was good. Most of the mishaps occurred when untrained MVAC technicians were servicing the system or the vehicle lacked the proper labeling to notify the technical that a hydrocarbon refrigerant had been charged in to the AC system.

The first study I wish to point out is Usage and Risk of Hydrocarbon Refrigerants in Motor Cars for Australia and the United States by I. L. Maclaine-cross , School of Mechanical and Manufacturing Engineering, The University of New South Wales, UNSW Sydney 2052, Australia

The author of the study calculated that there is the possibility of a hydrocarbon refrigerant fire in one out thirty million vehicular (30,000,000) use hours.

The second study is a flammability / ignition source study by Razmovski, V., 1994, , Safety of Hydrocarbon Refrigerants for Car Air Conditioning Systems, B.E. thesis, School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney, 97 p.

“Razmovski searched for ignition sources using a propane welding torch attached to a cylinder of hydrocarbon refrigerant. The car was parked in a sheltered outdoor position with fine weather. She started the engine and allowed idling until it reached normal operating temperature i.e., typically for ten minutes. She ignited the welding torch then adjusted it to give a stable yellow flame about 70 mm long. She extinguished the flame with an air blast and tested for easy re-ignition with lighted matches and cigarette lighter.

The extinguished torch was played over the hot engine, electrical, ignition and exhaust. Then the door, light and brake switches, fan motor, relays and cigarette lighter were tested in the passenger compartment. Each test took over fifteen minutes and 50 to 100 g of flammable refrigerant were used for each test depending on the model. Razmovski found no ignition sources either inside or outside the passenger compartment in the five cars tested.”

The third study is a good overall review on the use of Hydrocarbon Refrigerants. Performance and Safety of LPG Refrigerants I. L. Maclaine-cross E. Leonardi School of Mechanical and Manufacturing Engineering, The University of New South Wales, Sydney NSW, Australia 2052

The Abstract of the paper is as follows: “Ozone depletion and global warming require replacement of chlorofluorocarbon refrigerants-like R12. The hydrofluorocarbon R134a is non flammable, difficult to synthesize, has zero ozone depletion and high global warming. LPG refrigerants are highly flammable, occur naturally, have zero ozone depletion and negligible global warming. In Germany, most new refrigerators use R600a and many heat pumps and air conditioners now use R290 with measured energy consumption 10 to 20% lower than R12, R134a or R22. LPG mixtures have successfully replaced R12 and R134a in over 100,000 US car air-conditioners. Abboud (1994) measured the air-conditioner performance of five popular Australian cars with R12 and then LPG mixtures in our laboratory. He recommended 60% by mass commercial propane from Bass Strait and 40% commercial butane. This gave typically 10% more cooling than R12 with satisfactory superheat and typically 8% higher condenser pressure. Refrigerant property parameters show that R600a has half the leakage, pressure loss and condenser pressure and double the heat transfer properties of R12 and R134a. This explains the energy consumption savings of R600a refrigerators. Redesign of heat pumps and car air-conditioners for R600a could yield greater benefits. The insurance risk increment from LPG flammability for domestic refrigerators is zero. The increment for car air-conditioner is negative because of the high cost of R12 and R134a repairs. For large systems, ventilation of plant rooms and other LPG safety precautions can make insurance risk increment zero or negative if required.”

Flammability and Explosion Risk

Hydrocarbon based refrigerants are flammable. As stated before care must be taken when handling them especially when replacing a non-flammable fluorocarbon with a hydrocarbon Refrigerant. When charged into a normally functioning MVAC system it is my opinion that they are safe and the risk of a catastrophic discharge and subsequent ignition are very remote.

Hydrocarbon Refrigerants do not spontaneously combust on contact with air. Three elements need to be present.

• There needs to be a release of hydrocarbons.
• The Hydrocarbon Refrigerant needs to mix with the correct proportion of air, the range offlammability being between 2 and 10%. Outside of these limits combustion cannot occur.
• An ignition source exceeding 440 degrees C (824F) must be present.

If one of these three elements is eliminated, combustion should not occur.

The handling and use of hydrocarbons requires adequate safety measures. This is especially true if a system is being considered for retrofitting and replacing a non-flammable fluorocarbon with a hydrocarbon refrigerant.

That being said there are a few videos available where a controlled release of 12a was conducted in a vehicle and ignited with a spark plug with news cameras rolling and fire crews standing by.

The videos did demonstrate the flammability of the product but how often are spark plugs found in the passenger compartment that happen to be wired to proper power source of ignition.

That is not realistic in my opinion.

The last video is the explosion at UNSW with Dr. Ian MACLAINE CROSS intentionally placing himself in the passenger compartment of a passenger car and discharging two 170g cans of 12a and lighting a match. I will not spoil the video but he does not die and is seen at the end of the video in the hospital with his burns bandaged up and displaying somewhat of a smile. Now after seeing it ask yourself, after you notice a catastrophic discharge of your MVAC unit.

You smell it and see a white mist. And then you light a match or flick a lighter? Slim chance. More likely you would roll down your window and the ignition problem goes away as you dilute the concentration of gas in the process. If an MVAC system did catastrophically fail not all the refrigerant will escape. The remainder will stay in the system in equilibrium with the atmosphere.

Safe Handling and Charging Instructions:

The following video is representative of the safety precautions to use when working with a Hydrocarbon Refrigerant. While it is intended for commercial refrigeration if applies to MVAC applications.

• Proper PPE (Personal Protective Equipment) Should include:
• EyePro
• Neoprene Gloves (Prevents frostbite by keeping the liquid refrigerant from your skin)
• Cotton, non-flammable clothing
• Combustible Gas Detector (Ebay for $35.00)
• Flammable / Propane / No Smoking Sign for the area you are working in.
• Soapy Water to check for system leaks

Proper Tools

• Refrigerant Scale (Ebay for about $55.00)
• Refrigerant Pressure Manifold Gauge Set W/ Hoses and Connectors (Ebay for about $55.00-$200.00)
• Vacuum Pump
• MVAC Vent Thermometer (Resist the temptation to use an IR Gun Thermometer. They will not lock onto an air temperature. They only measure surface temperature. If you keep the trigger pulled in the temps will go lower and lower with the AC blowing on it. It won’t be accurate and you will think your system is working better than it actually is.)

The manner in which you maintain your safety and automobiles is ultimately up to you. The PPE and service gear may be viewed as overkill by some but in my option is a good investment especially if you have more than one vehicle to service.

NOTE: THE CAN IN THE PHOTO ABOVE IS ON THE SCALE TO BE WEIGHED IT IS INVERTED WHEN CHARGING THE PRODUCT INTO THE SYSTEM. 12A MUST BE CHARGED SLOWLY INTO THE SYSTEM AS A LIQUID.

DURACOOL CHARGING INSTRUCTIONS FOR MVAC APPLICATIONS

PLEASE KNOW: Once you convert your system over to a hydrocarbon refrigerant you may have difficulty finding a shop to work on it in the future. This is fine for my application but it may not be for yours.

I have taken the following directions for the DURACOOL website and added my own separated notes to them. Instructions from other brands are similar. Link to instructions and charging equivalents: Duracool® Technical Information – FAQ’S

Using DURACOOL 12a® to replace R-134a is extremely easy. DURACOOL 12a® is compatible with both mineral and synthetic oils found in both systems. You are able to use the oil that was originally installed in the system, mineral in old CFC-12 systems and synthetic oil in R-134a systems. We recommend that you use Duracool® A/C Oil Chill with OEM approved U/V Leak Detection Dye. Additional information on Duracool® A/C Oil Chill can be found by clicking on the A/C Solutions link from the navigation bar at the top of this page.

To replace CFC-12 Substitutes with DURACOOL 12a® requires the removal of all existing refrigerant. Charge the DURACOOL 12a® using 35% of the original (CFC-12) charge weight listed on the system tag. eg; system tag calls for 40oz of CFC-12, use 14oz DURACOOL 12a®. Since DURACOOL 12a® is compatible with the mineral oils there is no need to change or flush your system. DURACOOL 12a® will work with the existing components. Pull a vacuum to at least -10 in hg. If a vacuum pump is not available be sure to use Duracool® DuraDryTM to remove system moisture.

To replace R-134a with DURACOOL 12a® you must remove all the existing R-134a. Charge the DURACOOL 12a® using 40% of the original (R-134a) charge weight listed on the system tag. eg; system tag calls for 40oz of R-134a, use 16oz DURACOOL 12a®. Since DURACOOL 12a® is compatible with the synthetic oils there is no need to change or flush your system. DURACOOL 12a® will work with the existing components. Pull a vacuum to at least -10 in hg. If a vacuum pump is not available be sure to use Duracool® DuraDryTM to remove system moisture.

In Canada there are no requirements regarding the conversion of CFC-12 or R-134a to DURACOOL 12a®.

In the United States the EPA requires that systems using CFC-12 refrigerants must be retrofitted to R- 134a prior to the use of DURACOOL 12a® .

MVAC CHARGING PROCEDURE

PPE NOTES: Please use the PPE gear list above. Place your Flammable Propane Sign up so people can see it. Power up your Combustible Gas Detector and place it on the floor near your workspace. It will sound at times when you are making connections to cans and service ports and that is good. If it sounds and you have not performed an action that would cause it to go off. Investigate, take proper action like close the filling valves, and check for leaks. DO NOT MIX REFRIGERANTS!

Recover any existing refrigerant charge into a suitable container, regulations vary by region and the recovery of existing refrigerant may need to be completed by an authorized technician. Leak test the system, if a leak is detected the system must be repaired prior to charging. DURACOOL 12a® is flammable and should only be leak tested with an electronic hydrocarbon leak tester, soap bubbles or fluorescent tracer fluid. If leaks are detected, ventilate the area, keep away from flames and repair the leak. After repair, continue with the charging procedure. Pull a vacuum of at least 25 cm Hg (10 in Hg). If a vacuum pump is not available be sure to use Duracool® DuraDryTM to remove system moisture.

Locate the low side service port of the AC system. Generally, it will have a blue or a black cap (Do not connect to high-pressure side. This may cause components to fail and cause bodily injury.)

Remove low side dust cap. Connect hose to system by pushing on to the male service port fitting; ensure that the coupler fits snugly into place. The installation of a conversion service port fittings may be required to permit connection.

Using only a device designed for the purpose, connect charging hose to the DURACOOL 12a® container. Ensure that you are only charging liquid DURACOOL 12a® (invert the 6 oz. can) into the low side of system.

NOTE FROM DURACOOL TECH SUPPORT CALL: If you have pulled a vacuum on your system because it was opened to the atmosphere for repair, the Duracool Tech Support Department recommended that a liquid charge to the suction (low) side of the compressor should occur initially with the compressor off. Then one should wait about 30 minutes for the liquid to boil off to gaseous state and then move on to the next step with the compressor on. The use of an AC gauge set helps greatly to regulate the whole process and permit the system to be charged in a more precise and controlled manner.

After a minimum charge is achieved, start the compressor and set system to medium fan. When the compressor cycles on and off about every 45 to 60 seconds stop the flow of refrigerant. Check the vent for cooling. If cooling is inadequate or compressor is cycling excessively add small amounts of DURACOOL 12a® by opening and closing valve handle. Low side pressures should read between 28 and 45 psi.
Do not overfill. Exercise patience and let the system operate for several minutes before adding refrigerant.
Apply refrigerant identification tag on dry area near installation port.

DO NOT OVERCHARGE! Exceeding 60 psi on low side may damage compressor. In some cases, clearing the site glass overcharges the unit. Any overcharging may cause loss of cooling efficiency.

NOTE: A refrigerant scale and consulting the Duracool 12a equivalency chart from their website will give you an idea of how much product to charge into your system. It will be about 35-45% less than R-12 or R-134a

NOTE: Apply proper labeling (provided) to let others who may work on your MVAC system that is has been converted to a hydrocarbon refrigerant.

When charging systems with DURACOOL 12a® the pressures will be the same for the low side as factory ( 28 – 45 PSI) and about 5-10% lower on the high side than CFC-12 and may be as much as 20 -30 % lower on the high side for R-134a systems.

Here is a link to a Duracool Product Video which shows how to install the product with a simple provided gauge. Informative but it does not show the use of all the PPE and equipment I would like to see.

HELPFUL NOTES ON CHARGING A TOYOTA FJ60 WITH DURACOOL

1. The system should be converted to R-134a to comply with EPA law. Whether you do that or not is up to you.
2. My rig is a 1985 FJ60. The R-12 refrigerant capacity per the service manual is 1.4 Lb to 1.7 lb of normal R12 plus .9 LB to that. That = 2.6 Lbs total or 46.1 oz . According to the Duracool Charge Chart that is 15oz tops.. or 2.5 / 6 oz cans. I charged my system on a 70F day with 30% Humidity to 12oz of Duracool -12a. My low side pressure at that time was 20PSI and high side was at 150PSI. I was getting center vent temperatures of around 35F with the vehicle idling at 2000 RPM with AC and fan on high.
3. When the weather heats up I will recheck the pressures and system performance. As I was off the low side of the pressure-temperature charts. It is hard to AC work when it is cold. I will add or vent refrigerant as necessary.
4. Charging the system until the dryer sight glass clears with Duracool -12a will likely lead to an coolant overcharge. Watch your pressures and weigh out the refrigerant.

TEST DRIVE RESULTS:

As I mentioned my 1985 FJ60 is an Expo-Stye Build. I have Kaymar Rear Bumpers with Jerry Can and Spare Tire Holders, Front ARB Bumper, rear shelves and the whole lot. It is heavy and it taxes the 2F motor going up hills at freeway speeds. In mild weather (High 70’s) I was able to maintain freeway speeds while going up a local freeway grade and the AC on full blast and vent temps as low as 32F. I could not do that before with R-134a in the system. I will report back in when the temps climb here in Las Vegas with more results.

07/25/18 UPDATE:

We are now in the middle of the Las Vegas summer heat. High daytime temps today were 114F Humidity was under 10%. I took my FJ60 out for a drive and found the AC to be working much better than the R134 ever did. Center vent temps around 38F. I also took a 500 mile trip in 100-105F weather and found similar results. I still had to turn off the AC on extended and steep hill climbs while attempting to maintain freeway speed. Note: My rig is very heavy nearing 7000 LBS, which is over the US gross weight. I have added heaver duty brakes and rotor and have full float rear axles, 33 inch tires
and a 5 speed so it is basically Australian Specs for weight now. I need every bit of power I can manage out the the 2F motor under those conditions and the lower air density in the dry summer does not help one bit.

Conclusion:

I hope this write up has given you a through and unbiased understanding of Hydrocarbon Refrigerants and especially Duracool-12a. Only you can decide if they are a right for for you. In my view the EPA cannot allow Hydrocarbon Refrigerants for home use in refrigerators and approve a new flammable MVAC refrigerant R1234-YF without considering their original decision from the 1990’s on hydrocarbons.

I was not compensated in any way and purchased all the products and gear for this write-up myself and I am including links to products below as courtesy to the reader.

Duracool-12A and Manifold Gauges and Can Adapters Duracool Direct On Line Shopping © 2004 – Duracool Refrigerants Inc.

220 lbs Electronic Refrigerant Charging Digital Weight Scale with Case A/C HVAC 220 lbs Electronic Refrigerant Charging Digital Weight Scale with Case A/C HVAC | eBay

Harbor Freight Tool 2.5 CFM Vacuum Pump 2.5 CFM Vacuum Pump

FJC (2790) 1-3/4″ Dial Thermometer by FJC
Amazon.com: FJC (2790 1-3/4″ Dial Thermometer: Automotive

Portable Gas Leak Detector Propane Methane Sniffer w/Safe Alarm Sensor KXL-8800A Portable Gas Leak Detector Propane Methane Sniffer w/Safe Alarm Sensor KXL-8800A | eBay

FOOTNOTES:
Check your local State and Federal Regulations on MVAC regulations
Do Not vent refrigerants to the atmosphere (other than HC Refrigerants)
Do Not mix Refrigerants
Hydrocarbon Refrigerant 12a may be installed in a retrofitted R-12 system (second Generation) or a R-134a system.

It is illegal to directly convert a R-12 system to Hydrocarbon Refrigerant such as 12a Charging your MVAC system from your BBQ tank will work – however it’s only going to work for a short period of time. Once the compressor grenades be prepared to replace your compressor and the majority of the system component’s such as the Evaporator, Condenser. Expansion Device and maybe the hoses as well. Seriously Guys it has been done but I don’t advise it!

TECH TIP:

Your High side pressure should be approximately ambient temperature plus 100 if the temperature outside is 95, expect approximately 195 psi on the high side. In many cases it will be lower which is a good thing.

The Low Side pressure on most vehicles will be between 28 to 32 at 1000 rpm
Keep Cool this Summer!
DISCLAIMER: I AM NOT AN MVAC PROFESSIONAL THE INFORMATION IN THIS WRITE UP IS FOR EDUCATIONAL AND ENTERTAINMENT USE ONLY. THIS IS NOT ADVICE. THE INFORMATION MAY CONTAIN ERRORS. PLEASE USE AT YOUR OWN RISK