Here's some A/C knowledge I'd like to post that might clear up some questions that not everybody knows about. I've done quite a bit of reading on the subject and have formed some opinions that might help some of you.

I have two vehicles that still use R12, and since I don't plan on getting rid of them any time soon, and living in Arizona A/C is a must, I decided I would gain a little knowledge about it before I make any decisions to convert to R134a or continue to use R12. Like most of you I didn't buy a case of R12 cans or a 30 pound bottle when I had the chance. Right now R12 goes for about $38.00 a can retail and you must have the certification to buy it. So I figured it would be in my best interest to get to look into what alternatives I have.

First of all, R134a is not as efficient as R12. The new vehicles have larger compressors, evaporators & condensers to make up for this. A system converted from R12 to R134a may not be as cold as it was with the R12. R12 systems that were designed with a generous capacity might work just fine, but on the other hand, R12 systems designed with a marginal capacity might not cut the mustard. A 1975 Lincoln may have a system sized big enough to hack it, smaller economy cars that might not have been as generous in their design could be a different story. It may not be a problem in moderate heat, but in extreme heat you could notice a big difference.

Second, no matter what anyone tells you there are "drop in" replacements for R12. Autofrost, Frig12, Freeze12, Hotshot, etc. They are approved by SNAP (Significant New Alternatives Policy, a program established by the EPA). These are blended compounds, most containing R22, with other refrigerants, that are compatible with the R12 systems. The compatibility issue deals mostly with the oil, the term in the industry is Miscibility. R12 systems use a mineral oil, R134a will not circulate the mineral oil within the system, it's not "miscible" within the system. This oil is what lubricates the compressor, so without the synthetic oil (POE or PAG) that is "miscible" with the R134a, the oil stops circulating and the compressor burns up. POE & PAG oils are something like 100 times more sensitive to moisture as mineral oil is. It's not, to my knowledge, that the POE or PAG is incompatible with the mineral oil itself, but the tiny bit of moisture that the mineral oil can withstand is what's incompatible with the POE or PAG. So if there is a little moisture in your R12 system it might not be a problem, but converting that system with the simple conversion kits might create a problem.

If you don't have "barrier" type hoses you need to change them. The smaller molecular chains of R134a and the R22 (that is contained in most of the replacement blends), will seep through the microporous rubber hoses that were installed on most R12 systems.

There's also the problem with chlorine oxides in the system. If you've ever had R12 in the system, the aluminum parts have formed a chlorine oxide layer on them that cannot be flushed out. The R134a reacts adversely with the chlorine oxide and the result could be something called "Black Death", you can find out more about that on the web. And my understanding of that is, if it happens you remove everything from your system and throw it in the trash and replace basically everything. Not a good thing. In all these cases my suspicion is that it’s the moisture that’s the catalyst. As long as you never introduce any into the system you might be fine.

I personally know at least one person that did a quick R134a kit conversion. He didn't remove any mineral oil, just added the R134a and the oil charge that came with the kit he bought. He admits it's not as cold as it was with R12 but it works and he's happy. The point is, even if you do everything right you'll end up with a system that just might not do the job that you want or need.

My advice is this: If you have an R12 system, stay with R12 or an approved substitute. In most cases these substitutes can be added right to the R12, and work just fine. The only problem with that is there might be an EPA law prohibiting this. At any rate, when you do this you end up with a blend that contains R12. And if you ever have to have your system evacuated by a certified technician, following all the EPA rules, it’s now no longer pure and could be a disposal problem. There is a distillation process that can remove the R12 from the gas blend, but it sounds expensive to me. Like motor oil contaminated with anti-freeze, no body wants it. R12 removed from your system can be reused back into your system or reprocessed and used again. But once it’s blended with anything else it could end up being treated like hazardous waste. So if your system is appreciably low it would be best to evacuate all the R12 and replenish it with only your chosen substitute. Once you do use an alternative gas your system by law has to have special fittings put on them that have specific threads based on what substitute you do use, and a sticker on there identifying what it is.

I would never try to convert a system to R134a. You may have done it already with favorable results, and if so good for you. If you're thinking about it, I would consider some of the factors I've outlined before jumping head long into it.

Here's what I did: I decided I wanted to go with a hydrocarbon refrigerant. I choose them over the other refrigerant blends like Autofrost, Frig12 & Freeze12 because you don't need a certificate to buy them. I bought a case of Duracool from an ad on the web. I did this before I found out that hydrocarbon refrigerants were not approved by SNAP (in other words illegal to use). I also later read on one of the A/C message boards where a guy in southern Arizona used a mixture of propane and butane (hydrocarbons) in his system with good results. I thought I might have a leak in my system so I didn't want to lose my new Duracool, so I decided to try this first. He used a 60% propane, 40% butane mixture in his first car and found it worked great. He found that mixture was too cold for his second vehicle and adjusted it back to 50/50. I was trying for a 55/45 mixture with mine but ended up with more like a 40% propane, 60% butane mixture, but that's another story. And it's working great so far so I left it at that. My 81 F250 has an R12 capacity of 60 oz., that would have cost me almost $200.00 in R12 gas alone. And I'd be putting it in a system that I'm not sure has a leak or not. By using 40% of that (R12 is heavier by volume than hydrocarbons) I filled the system for about $4.00 - $5.00. I used Coleman lantern bottle propane and iso-butane used for those portable one burner stoves. BBQ propane is not propane, it’s LPG (Liquid Petroleum Gas), mostly propane by the exact contents can vary.

Flammability: Although R12 is not flammable, R12 with the oil in it is. R134a is supposedly non-flammable but on it’s MSDS it says has an autoignition temp of >743 C (>1369 F). Duracool, and I take it the other hydrocarbon refrigerants also, says it’s flammable and has an autoignition temperature of 891°C 1636°F. Not sure how that works. And of course propane & butane are very flammable, but is this a concern and if so how much of one? Before the propane & butane were introduced to the system it was evacuated by drawing a vacuum, no air, no possibility of any internal fire or explosion hazard. All hoses, fittings and connections are under the hood, everything inside the interior of the car is hard piped. With the most probable sources of a leak under the hood the heavier than air gasses can escape similar to that of gas fumes. Also, propane & butane are very fussy as far as their correct mixture with air, that’s why all your BBQ grills and torches have a specifically designed head to draw in just the right amount of air in order to get an ignitable flame. The most likely source of a catastrophic system leak would be from a frontal impact. The condenser is the first thing to be damaged, the gas escapes and unless someone is there immediately with a Bic lighter, it’s gone in seconds. Is there any danger? I suppose there is a remote possibility. Nobody can rule it out 100%, but is it realistic? If you feel it’s unsafe, think about some of those 70’s trucks with 18 gals of gasoline behind the seat.

Another tip: If you have any of those coast guard approved air horns, the kind you use on a boat or take to a football game, check the label. If they say dichlorodifluoromethane, that's R12. They came out of the same plant, put in the same cans, only the labels they painted on them were different. I recently filled one of my vehicles with one can of regularly labeled R12 and two cans of "air horn gas".

If you can do your own maintenance in this area you’ll save yourself a lot of money. When these laws were passed you can be sure the chemical manufacturers, equipment manufacturers and representatives of the air conditioning service industry had their ducks in a row and lobbied hard to ensure the restrictions went in place the way they did. I’m not saying their hearts weren’t in the right place. But one thing they did do is shut the shade tree mechanic out of doing any AC repair. That’s why it costs a million dollars to fix your car A/C. And even if you don’t have the equipment or desire to do it yourself, just knowing your options can help. So the next time you go into a shop where they tell you they have to replace your entire system to the tune of $1200.00, you know you can walk out of there and go somewhere else.

I hope this helps some of you with A/C questions.

 

Hope you don't blow your self up messing with blends. Im really suprised that after finding out that what you were going to use was flammable you continued. There have been reports of evaporater exploisions using blends. Also be advised that even though blends have EPA approval all that means is that it is not going to harm the o-zone. They do not state that any of them are safe for use in autos or that any of them will cool adequately. The only other approved and tested refrigerant for auto use other than R12 is R134A. I had to buy an expensive tester just to make sure that a vehicle I was preparing to hook up to my expensive recycling machine did not have and unknown refrigerant in it. It has paid for its self twice this year. Some of this stuff is highly corrosive and some is highly explosive please be careful.


2000 XLT Flare Supercab Sport 5.4-Auto-355LS-Tow pkg-Bedrug-Xtang Tonneau

 

Enviro safe and duracool woork very well in stock system and you can roll your own but do not use butane. The proper mix is an isobutane (butane with forked carbons on one end) and propane.

A straight propane mix or promane and straight butane mix will likly damage your system.
Straight Propane has too high a pressure.

Some lighter refills have isobutane as well as some mountain/high altitude camp stove fuels as it stays liquid at lower temps.

The use of Duracool or enviorsafe is legal with EPA as long as you have first done a legal conversion from R12 to R134. This is part of screwy R12 ozone laws.
Some states do not allow hydrocrbons in vehile AC systems some do but to say that use of duracool is flat illegal is not true.

I have used them for years with excelent results and no changes to oil or hoses are needed.

 

Well, the imformation is well appreciated. I can say this, my head is buzzing after reading that one! Why didn't they just stick with R-12 in the first place? It cools better and is safer. It seems like those A/C are very complicated. I can honestly tell you I don't totaly understand how they take a gas and get cool air at the other end. I think I will wait untill next summer before I do anything to mine. It works, but sometimes it shuts off and I have to wait 5 min and turn it back on.


'90 1/2 ton 4x4 XLT Lariat
RC LB w/5.0 EFI M50D 3.73gear
true duals w/glasspacks

 

[font size="1" color="#FF0000"]LAST EDITED ON 16-Aug-01 AT 03:06 AM (EST)[/font][p]In my earlier post I eluded to the fact that there might be a problem with mixing refrigerants and complying with the EPA laws, I have since found this quote:

Federal law prohibits topping off A/C systems with any refrigerant which is different from what’s already in the system - unless all of the old refrigerant is first removed so the system can be converted to a new refrigerant.

It was suggested that if your first converted your system to R134a you could then convert it to a hydrocarbon refrigerant (HC). But according to the EPA website, they have a list of "Acceptable" substitutes and a list of "Unacceptable" substitutes. Enviro safe and duracool and all other HC's are listed under the "Unacceptable" substitutes. It then goes on to define Unacceptable as; illegal for use as a CFC-12 substitute in motor vehicle air conditioners. So I really don't see how converting to r134a first would then make it Acceptable.

The US is the only place to my knowledge that has these restrictions on HC refrigerants, they're used extensively in other countries. I was quite surprised to find out that R12 is still being produced in other countries and also still produced in the USA, but for export only. These are facts that I admit I haven't spent any time to verify, and I won't. Just like the rumor that has been spread around that Dupont's patent on R12 was about to run out, I've since heard that was false too, but either way does it matter? R12 is still $38.00 a can. And if there's alternatives out there that make more sense than an R134a conversion, why not? I can burn propane in my BBQ and let it run as much as I like while I try to get it lit, and not problem. But if I put it in my AC I'm killing the environment? I can't vent off my R134a system to the atmosphere, but yet I can put the same can of R134a onto a blow duster tap and blow out my computer all day long with the EPA dragging me off to jail. It's the exact same stuff. The only difference is with the way the new laws are they're getting into your wallet now.

 

You have only to look and then you can see.

Cut and pasted directly from the the EPA website anwsers to FAQ

*** added
"10 Is it legal to replace HFC-134a in a motor vehicle with hydrocarbon refrigerants such as DURACOOL 12a® and HC-12a®?

In certain circumstances, the replacement of HFC-134a in a motor vehicle with hydrocarbon refrigerants might be permitted. At a minimum, in order to avoid violating the Clean Air Act, the motor vehicle A/C system must have either been originally designed for use with HFC-134a refrigerant, ***or must have been previously retrofitted from CFC-12 to HFC-134a refrigerant***, AND no sham retrofit must have occurred to convert the system to the hydrocarbon refrigerant. In order to avoid violating other laws, the replacement of the refrigerant must not violate any state or local prohibition on the use of flammable refrigerants in motor vehicle A/C systems."

So as you can read there is a EPA legal way and as long as you have the 134 fittings (which you need for the duracool or enviorsafe) you tell me how the EPA knows that you did not do it the "right" way.

Using n-Butane instead of isobutane risks the compressor getting the liquid form and slugging the compressor hence the need for the isobutane with the propane.
Using straight propane runs too high pressure hence the need for the mix.

This is all well laid out on the alternate AC board.
Like I said I have used these mixes for years and have had no probs to date. In my state they are legal. But of course you situation may be different.

 

Let me try this a different way. I did not mean that anything you stated in your post was inaccurate. As far as I know the info provided is well researched and true. I have heard all this at many A/C seminars. Using other refrigerants isn't illegal. Again the EPA (as far as I have been advised) has passed a lot of different blends,to be safe in as far as it won't destroy o-zone if it escapes. Only 2 kinds are currently accepted by the Auto industry. R12 and R134A. You can use what ever you like. Please be carefull some of this stuff can blow up and has. Its like the reloading I do. One mistake and I might not have another chance. I use a refrigerant identifer so I won't be one of those unlucky ones to have a problem caused by someone mixing blends and then comming to me for service. All refrigerants are to be labled but not all are. This is a fact. What happens when I add something else to the blend because I didn't test it? Maybe nothing maybe boom. I'll end with just be carefull.


2000 XLT Flare Supercab Sport 5.4-Auto-355LS-Tow pkg-Bedrug-Xtang Tonneau

 

Not directed at your post Nitro it was to explain to PM that his legality claim was false.

Yes it is flamable in proper concentration in the air.
However despite extensive use down under there are only two possible cases of probs and both involved vans with bottles of flamables like acetylene(much wider conc range of flamibility) or flamable flat fix that likly leaked and caused prob. Thus while flamability exists extensive use in actual AC units has not shown a prob. But in todays USA legal envior you could not even get aspirin aproved for use so I am not suprized that automakers avoid flamable types. Also the automakers are not faced with trying to find a substitute to use in a system designed for R12. They got to design a R134 system from the ground up which is very different then trying to get good cooling from an system designed for R12.

For extensive info on alternative refigerents with posters of varied opinions I suggest this link.

http://aircondition.com/wwwboard/alternative/

Then decide for yourself.

 

[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 03:51 AM (EST)[/font][p][font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 03:49 AM (EST)[/font]

[font size="1" color="#FF0000"]LAST EDITED ON 20-Aug-01 AT 03:46 AM (EST)[/font]



|I personally know at least one person that did a quick R134a kit conversion. He didn't remove any mineral oil, just added the R134a and the oil charge that came with the kit he bought. He admits it's not as cold as it was with R12 but it works and he's happy. The point is, even if you do everything right you'll end up with a system that just might not do the job that you want or need.|
[QUOTE]

To start of I am not saying anybody is wrong I'm just adding my 2 cents. if converted properly R134a will cool just as cold as R12. bieng a IMACA Certified Tech for A/C, i have done a few conversions myself and always install an eletric pusher fan on the condensor. the molicules of the R134a need the extra air flow to cool as well as the R12.also check between the radaitor and condensor for grass, leaves, trash or whatever. if your air flow is restricted neither R134a or R12 will cool very well. if you are going to use a "blend" please be carefull, I worked with a man who hooked his gauges to a car serviced in Mexico, needless to say he is no longer with us. along with the two cars on either side of him in the shop. always us an identifier and be sure you know what you are doing. good luck to all and cool driving.



(sorry about the edits, just trying to figure out the whole quote thing.)