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tuna55 HalfDork
6/21/10 9:05 a.m.

Folks, I have to charge my AC in the Volvo (1991 940 wagon because the high side fitting leaked) and I also have to convert it from R12.

Has anyone used the magic "R12a" duracool/redtek stuff? I know it's illegal - I don't care. Is it better than R134a like they claim?

cxhb Reader
6/21/10 9:38 a.m.

If I remember correctly my first vehicle, an XJ cherokee, had R12 until i sold it. It would freeze you out of it.

tuna55 HalfDork
6/21/10 10:17 a.m.

OK, just to be clear. R12 is not R12a. R12a is hydrocarbon based. It's also not patented by Dupont, so it's cheap. I am interested in R12a.

No posting about flammability, by the way, you guys are smarter than that anyway.

aircooled SuperDork
6/21/10 10:29 a.m.

Those "compatible" refrigerants are usually just blends of standard refrigerants from what I have seen (I have used Envirosafe). Are you sure it is illegal? I have heard of at least a few people having good success with the various substitutes. As with other things, if the system is well setup, the refrigerant isn't as critical of a factor as you might expect.

One note: If you do use the blends, an AC shop will likely not want to work on your car. I don't know what they would do to evacuate that sort of system without contaminating their stuff. Would they notice?, I don't know.

Dr. Hess
Dr. Hess SuperDork
6/21/10 10:39 a.m.

Yeah, they'd notice. They have tests to make sure you don't dump garbage into their Freon tank. I've always thought concerns about flamible refrigerants was kinda silly in an automotive environment as you drive around with 10-25 gallons of gasoline right behind your seat.

tuna55 HalfDork
6/21/10 11:32 a.m.

Thanks Dr. Hess for the obvious flammability argument closing statement. I also would have accepted the flash point of the flammable R12a being 500 degrees F higher than R134a.

I am sure that the EPA doesn't allow it for use in your car. I am sure it isn't a blend of Dupont branded refrigerants. I think it's a mixture of propane and/or butane and potentially some of the Dupont stuff in there as well, but it's the other junk that makes it non EPA worthy. Probably because Dupont hires some good lobbyists. Either way, I don't care what the EPA says about this.



I also know that I won't be able to get it serviced without evacuating it first, I am okay with that.

I would also like to know how you judge the 'drying' products which claim you can run a bit of them in the system in lieu of pulling a vacuum. I don't have a vacuum pump and no auto parts nearby rent/loan them. I am not sure a local AC place would just pull a vacuum for me and leave it like that.

tuna55 HalfDork
6/21/10 11:36 a.m.
aircooled wrote: Those "compatible" refrigerants are usually just blends of standard refrigerants from what I have seen (I have used Envirosafe).

Tell me more about this stuff if you can.

triumph5 New Reader
6/21/10 11:39 a.m.

In reply to tuna55:

Learned this from a a friend. Use a working compressor from an old refrigerator. It will pull a vacuum (fittings, etc) enough for you to work on your A/C system. Local land fill, frig on side of road, and there's your vacuum pump.

tuna55 HalfDork
6/21/10 11:40 a.m.
tuna55 wrote:
aircooled wrote: Those "compatible" refrigerants are usually just blends of standard refrigerants from what I have seen (I have used Envirosafe).
Tell me more about this stuff if you can.

It would appear this is another brand name for R12a

ClemSparks SuperDork
6/21/10 11:41 a.m.

Too bad it's so heavy...I'd offer to ship you this one (vacuum pump) I have as a loan. It's old but looks like it will work good.

TucoRamirez Reader
6/21/10 11:43 a.m.

I squozed a can of the new stuff into my 97 camaro a few weeks ago. It's worked fine since. I think my only problem was the leak caused when I loosed a nut on the a/c line while trying to make room for something else. That was a good day for goggles.

m4ff3w GRM+ Memberand SuperDork
6/21/10 1:11 p.m.

I have a licence to buy R12, but since I needed to refill the whole system I used EnviroSafe "Industrial 12a" in my wife's Benz.

The stuff works very well.

Envirosafe is a hydrocarbon refrigerant.

Duracool and the like are blends of R134a and other refrigerants that will carry the oils currently in your system.

tuna55 HalfDork
6/21/10 2:57 p.m.

I must say, the ZOMG!!!!+++111 talk on places like corner-carvers has me miffed a bit on the hydrocarbon thing, but I dunno. It's more the "it doesn't work as well as they say compared to 134a" or the "seals and junk are not going to be any better than with 134a" stuff that perks my ears. It is sounding a lot easier just to bring the car to a shop and let them handle the vacuum and recharge, especially after the ZOMG!!!!+1111 talk.

m4ff3w GRM+ Memberand SuperDork
6/21/10 3:03 p.m.

I got no dog in the fight, but I think the ZOMG!!!!+111 people are goofy though. I'd be much more concerned with the fuel in the tank than 12oz-16oz of propane/butane.

Instead of taking in somewhere, do this if you are hesitant of the HC thing.

  1. Borrow w/deposit vacuum pump from your FLAPS

  2. Buy adjustable orifice tube ~30

  3. Buy new dryer/accumulator

  4. Buy oil and R134a from FLAPS

  5. Drain old oil from compressor

  6. Replace the accumulator/orifice tube

  7. Vacuum down for an hour

  8. Let it sit and make sure there are no further leaks

  9. Charge up with R134a.

tuna55 HalfDork
6/22/10 7:11 a.m.

No vacuum pumps available to borrow or rent from the local stores. Other than that it's all done with the exception of the weirdo leaky high side fitting.

phil8192 None
7/21/10 12:07 a.m.
tuna55 wrote: Has anyone used the magic "R12a" duracool/redtek stuff? I know it's illegal - I don't care. Is it better than R134a like they claim?

Duracool isn't illegal; it's just hard to find a garage that will do the work for you, because most air conditioning technicians paid a lot of money for that fluorocarbon license and they want to keep the business as proprietary as they can.

Duracool is simply propane, albeit a highly refined version compared to what you buy for your barbecue. Cooking propane may contain fractions of ethane, butane, etc., plus some moisture. When you buy a can of Duracool, it's been refined to get rid of most of the other molecular weight hydrocarbons and is guaranteed dry, so it won't damage air conditioning system parts. (Sorry, m4ff3w -- I've had extensive exchanges with the Duracool folks, and they tell me it's just highly purified propane, that's all.)

Being a hydrocarbon and not a fluorocarbon, Duracool is 100% compatible with the lubricants used in R12 and R134a systems. There is no need to remove the oil and replace it with anything else. It is also compatible with all the elastomers used in refrigeration O-ring seals, hose linings, etc.

If you want to use Duracool in your vehicle, go for it. You'll need to get the R134a conversion kit for your fittings, just as if you were preparing to put R134a into the system, but that's all. Regular air conditioning service manifolds, gauges and hoses will work for the job.

Bear in mind, because Duracool is propane, it is flammable. That's not as bad as it seems, though. The total amount of refrigerant in an automotive air conditioning system is typically less than 2 lb., and because Duracool works much better than R12 or R134a, you may only need a pound, or so, in the system for equivalent cooling efficiency. If your vehicle catches fire, you'll have much more to worry about than a brief propane flash fire, anyway. Also, consider this: If R134a is exposed to a flame, it decomposes into phosgene gas, and if you get a good lungful of that, you're dead. If your car engine catches fire with R134a in the cooling system, you'd better run upwind like hell if you value your life. (A couple of summers ago I encountered a disabled diesel-powered ambulance in a shopping center parking lot. It had sprung a leak in the air conditioning system. They had started the engine to help get it loaded on the flatbed tow truck, and as I walked behind the ambulance, I got a slight whiff of its exhaust. The leaking R134a had been sucked into the engine air intake and passed through the cylinders, decomposing as it went. I caught my breath, but what little I did get into me burned my nose and throat. If I'd gotten a lungful, they'd have been calling another ambulance to cart me away.) If you've been around propane powered forklift trucks, you know their exhaust is fairly benign, and that's why they're often used at loading docks and in warehouses.

Since Duracool is essentially the same chemical used to fire up your backyard barbecue, it is not considered a greenhouse gas and can be purchased without an HVAC license. That's a plus.

I've used ordinary cooking propane in my home split air conditioning system, and it's been working fine. It's an old R22 system, and it has a slow leak somewhere in the plumbing, enough to require a full recharge each year for a couple of hundred dollars each time. Rather than spending the $7K, or so, that it would take to fully replace the system, I decided to vacuum out the system and replace it with propane. I've been delighted with the results. The leak is outside the living space and very small, so I don't even smell the odorant that's added to the gas (the "skunk" or "rotten egg" smell), either inside or outside the house. If the air conditioner stops working, I just grab a 1-lb. disposable cylinder of Coleman stove propane or what-have-you, hook up the hose to the fill valve and dump the gas in, and it's good to go for the summer. (The biggest problem was finding an adapter that would go from a disposable cooking cylinder to air conditioning service fittings. I think I ended up fabricating my own from brass parts scrounged from camping outfitters and hardware stores.)

A couple of caveats: 1. Air conditioning systems don't like air. Air doesn't harm the system, but it's a lousy refrigerant, so you need to get it out of the system. Purge your service hoses with Duracool/propane before you hook them up to the system. 2. Air conditioning systems don't like moisture. The moisture attacks metal parts and will eventually cause the compressor valves and rings to fail. That's the main reason systems get vacuumed out for hours and hours; it's not the air so much as the water vapor that needs to be removed.

Water is heavier than propane. To improve your chances of not getting water into the system if you choose to use cooking propane, chill the bottle upside down in the freezer for an hour or two. Then, before you hook up to the air conditioning system, purge the bottle for a second while holding it upside down. If there's any condensed water in there, it will be blown out during the purge.

If you don't own a vacuum pump, and don't care too much because your car is no longer in showroom condition, you can still charge the system with cooking propane and make it work. Fill it up with the gas, then open the valve and let it leak down to nearly atmospheric pressure. You may want to run the compressor briefly to mix things up and push the propane through the system. Make sure the engine is OFF when you purge the system and do the work out in the open air, so an inadvertent spark doesn't send you to the Moon. Repeat the fill/purge process four or five times. By the time you've done it the fifth time, you'll have vented $1 of propane and gotten rid of 99.999% of the air and moisture in the system -- and a $1200 commercial vacuum pump sucking for five or six hours could hardly do better.

When you run Duracool or propane in an automotive system, stay with the recommended performance numbers for vent temperature in the vehicle cab, which is more important than the weight of refrigerant in the cooling loop. If the system gets too cold, it will ice up and stop blowing cold air. If that happens, you may need to release some Duracool to tone down the performance. Typical temperature at the vent should be no lower than 34-36 degrees Fahrenheit, just above freezing, with the windows rolled up and outside air vents closed.

There's a short 3:42 minute official Duracool video at YouTube (v=E2ESleWa1nI) that shows the general procedure. Disclaimer: I have no affiliation with either Duracool or YouTube.

foxtrapper SuperDork
7/21/10 7:17 a.m.

You can still buy R12. There's plenty on the market, just look on ebay for example. Getting the licence is easy enough.

Without a vacuum pump, you're gambling on the air contamination. You're also limited to R12 or one of the supposedly mixible chemicals.

tuna55 HalfDork
7/21/10 7:18 a.m.

Wow, that was an informative post. I will use that in the future for sure. The flip side is that I had a shop charge me up with R134a (and found and did not repair a slow leak at the compressor) a few weeks ago.

twolittlebroncos New Reader
7/21/10 8:29 a.m.

I looked into Duracool when I still had a R12 car. Everything I read indicated that the stuff worked well like R12. I believe propane based refrigerants are used heavily in tractors etc.

When I was getting my R134 system serviced a couple weeks back I asked the technician about propane refrigerants. He said they work great, but they're flammable. You've already addressed the flammability issue.

Only other things I would consider are future evac issues or if you're planning to sell the car someday.

spitfirebill Dork
7/21/10 12:05 p.m.
m4ff3w wrote: I have a licence to buy R12, but since I needed to refill the whole system I used EnviroSafe "Industrial 12a" in my wife's Benz.

How difficult is the test you have to pass to get this license?

foxtrapper SuperDork
7/21/10 1:16 p.m.
spitfirebill wrote: How difficult is the test you have to pass to get this license?

Skim over the answers booklet, then check the box on the short open book test. Send in your fee, and get your licence mailed to you.

I did it online some years ago. Quick and easy. Think it cost $25.

m4ff3w GRM+ Memberand SuperDork
7/21/10 6:53 p.m.
spitfirebill wrote:
m4ff3w wrote: I have a licence to buy R12, but since I needed to refill the whole system I used EnviroSafe "Industrial 12a" in my wife's Benz.
How difficult is the test you have to pass to get this license?

As Foxtrapper said, it is easy as pie. Mine was $25 as well.

7/29/10 8:03 p.m.

Has there been any of those AC techs yet warning of the the Danger-danger it is propane on this thread. It is amazing to talk with people that I consider to be intelligent spouting all the danger stuff. Ok, you are driving around with 20 gallons of very volatile gasoline and it is pumped to the injectors under pressure and they worry about a few ounces of propane. In the 1970's I ran a work van 300,000 miles on a converted to propane / gasoline system. I had a big tank hanging off the back of my van, hit multiple times while driving for a living and nothing happened.

Plus ever look at the MSDS sheet on 134a? Take a look where it says, "AUTOIGNITION TEMPERATURE: >750°C " "R-134A is not flammable at ambient temperatures and atmospheric pressure. However, this material will become combustible when mixed with air under pressure and exposed to strong ignition sources." Holly smokes batman, 134a can burn too and forgive me but the high side is a good amount of pressure.

Ask the AC tech harbingers of doom if they ever read the sheet.

If I remember my chem classes, propane would flash but you would need to have a lot puddle to get any decent size flash.

There are entire Nations (internet search) that are going to require hydrocarbons be used in cars. They are requiring refrigeration units to use hydrocarbons. There are something like 10 million cars running AC hydrocarbons and there has not been one blow up.

Now here in the USA since Dupont pays a lot of tribute to the people in government, they are probably trying to outlaw hydrocarbons. Sometimes I wonder if I am living in the free world anymore? The next great Dupont wonder is going to be 300 low side and 1800 high side. That will put an end to people working on their own system.

MrJoshua SuperDork
7/29/10 8:41 p.m.

I don't really have a dog in this fight buuuuuut, I see a logical disconnect with saying we have a bunch of gas in the tank so we shouldn't worry about propane in the AC. The difference is, the AC system runs through the interior of the car. AC systems usually leak by the time they are 10 years old and flammable gas leaks in enclosed spaces are a recipe for disaster. Even worse, the reason to change to a new type of gas in the system is if your system is leaking. It is really common in the AC world to just top up a system instead of repairing it. Soooo, the only similar comparison would be to say: I don't worry about propane in my AC because my cars fuel lines run through my passenger compartment and leak a little and that has never caused me any problems before.

shadetree30 Reader
7/29/10 9:13 p.m.
spitfirebill wrote:
m4ff3w wrote: I have a licence to buy R12, but since I needed to refill the whole system I used EnviroSafe "Industrial 12a" in my wife's Benz.
How difficult is the test you have to pass to get this license?

IIRC most of the questions deal with what you aren't allowed to do, not A/C theory.

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