Difference in opinion on old R-12 Freon vs. the new stuff


My 1991 BMW needs a new AC system. Two very reliable mechanics suggest different routes to the problem, both are within a hundered or so dollars of each fix. One suggest continuing to use the old R-12 (presumably colder) while the other suggest converting to newer coolant. Price is $60 lb for old R12 while new stuff is $12 or so. Problem is, if I need freon in the future, say for a leak then I will pay through the nose. Any suggestions on how to spend $1200?


Since you are the owner, the choice is all yours. It’s an opinion type of deal. There may be environmental reasons to use the new refrigerant.


As I understand it, R12 is a more efficient refrigerant, and older vehicles converted to use R134a need have more work done than simply replacing one with the other for maximum efficacy. The $1200 quote sounds like it would include those changes, so I’m with the previous poster - flip a coin and pick one. Environmental concerns and cheaper subsequent repairs would probably sway me to pick the new stuff.


I agree that it is a tossup, but I would go with whichever is the cheaper option (assuming it is a quality job) because you never know how much longer the car will last.

I had a 1989 Accord in which the compressor seized several years later. I opted to go for the retrofit to R-134a, rather than keeping R-12. Before the retrofit, the A/C blew ice-cold air. Afterward, it was cool but not nearly as COLD as it was before. My current 2003 Accord blows ice-cold with R-134a, but it was designed to use it from the start.


I really depends on the capacity of the condenser and evaporator in your car. Some cars that were designed for R-12 will not do well with R-134a. I tried “converting” one of my old benzes to R-134a several years ago and was never happy with the AC performance. I eventually switched back to R-12 and the results were much more satisfying. You may want to check a BMW forum and see how your car will pergorm with R-134a.

The main downside is cost, most AC shops are charging about $50 per pound for R-12, so a recharge will cost about $150 is you ever develop a leak. You can buy R-12 yourself, but you are supposed to have a license. In reality, you can obtain a license buy taking an on-line, open book test for about $15. There is always R-12 for sale on ebay, and (I’ve heard) those sellers rarely ask for proof of a license.

IMO, use R-12 unless cost is a concern.


It may depend to some extent on where you live and how much longer you plan to keep the car on the road (forever?). If you live in Barstow or Houston, you probably want as much cooling as you can get and maybe ought to stick with the R-12 system even though future repairs to the system are going to cost a fortune. If you live in Seattle or Caribou, Maine, there just aren’t that many days a year when you will need killer air conditioning and an R134a conversion may be more than adequate even if it turns out not to be quite as good at cooling and dehumidifying.


If a conversion is done properly, you will barely notice the difference in cooling ability. I live in Florida, have no tint on my windows, and my converted system can get the cabin down to 72 on the hottest of days. Colder if I choose. That’s with all original factory installed parts, just with converted refrigerant. R134a (the new stuff) is better for the environment, cheaper, easier to obtain, and DIYer usable.

Make the switch.

I’d also suggest seeing if you can get a lower price on the conversion. You might be able to get it closer to 900 or 1000 if you look.



Properly done by someone who knows what they’re doing R134 works fine and will get just as cold as R12; at least in my experiences.


True for some cars, but R-134a has significantly less cooling capacity than R-12. If the sizing of the evaporator and condenser is marginal for your climate (typical for older german cars in the southern U.S.), you will not be happy. I know some folks who have installed larger condensers on their old benz and have acceptable results with 134a. My experience was that the AC performance was “OK” up to about 85 or 90F, then it became inadequate to keep the car comfortable. Again, I would talk to BMW owners that are using 134a in your climate and see if they are happy.


BTW, if you are interested in recharging your own R-12 system, there is no shortage of R-12 on the market at a decent price:


Note that you are supposed to have a license to buy this stuff.


I think this boils down to personal preference. I can say that the 88 Honda Accord I used to own had the absolute coldest butt-freezing A/C I have EVER seen in any car. If you elect to stay with R12 and ever need a recharge, you can find this stuff called Freeze-12 that can safely recharge an old Freon system. I used it in the above-mentioned Accord without any trouble at all.


I have no problems coaxing 30-40 degree air out of an A/C with the use of 134, even on those hot 100+ degree Oklahoma summer days.


I would avoid “Freeze 12” and other “alternative” products because you may have a problem getting your system serviced in the future. Most AC shops do not want to “recover” these coolants (other than R-12 or R-134a). BTW, Freeze 12 is just a blend containing mostly R-134a. Do yourself a favor and limit your choices to R-12 or R-134a.


And are we all forgetting that R12 kills mother nature? R12 is gonna give you a slight advantage in cooling capacity, which you will likely not notice, and if it leaks it’ll kill ozone. Why not just use the R134a?



I understand the concern, but you have to understand that no new R-12 is being manufactured in the U.S. or imported (legally) into the U.S. The available supply is all recovered and reused. Like it or not, that existing inventory will all eventually (slowly) find its way into the environment. The price of the remaining stock will probably continue to increase until fewer and fewer people use it. One individual refusing to use R-12 will accomplish nothing, the total supply will remain the same.

The R-12 ban did accomplish its goal, new systems are designed to use alternative coolants an no new R-12 is being introduced. At this point, I don’t believe R-12 from automotive systems is a major contributor to ozone depletion.


In my opinion, there are two important factors in how successful a conversion will be. The first is the design of the AC system to start with. Every model is a little different and sometimes swapping the minimum will not work well. As mentioned, a bigger condenser can do wonders if that was the choke point of the old system.

The second is the knowledge of the converter. Conversion with good results is straightforward if you are lucky. If you have one of those models good for you. If you are not lucky, you need someone that has seen a '91 BMW AC system before. If both of these guys have done this model before, you are back to flipping a coin. I would try a Beemer board and pay attention to conversions in '91s or other MYs with similar AC systems.