R-12 Air Conditioning
 

There is lots of confusing and conflicting info out there about how to handle cars with R12 refrigerant. At $50-60/lb, R12 is no longer an economically viable option for those of us with older cars. Conversion to R134 can require changing a lot of parts including compressor, drier, expansion valve, and pressure switch. This hardware amounts to about $400 on a DIY basis. This does not include flushing the condensor and evaporator and recharging. Maybe another $200 if done by a shop.

Then there's Hot Shot which you can buy at Kragen and the like. But it contains R22 which contains many bad things for your system. Or you can try Enviro-Safe ES-12A. This stuff appears harmless expect it contains flammable ingredients and thus has not been approved by the EPA. (Worried about possible fire or explosion, particularly in an accident.) But you can buy Enviro-Safe without an EPA certificate. Then there's Freezone (RB276) which appears to be perfect but requires an EPA certificate and is only available in 25# (about $220) containers. (An EPA certificate can be gotten for $20 and some testing hassle via the internet but not really a big deal.)

Although against EPA regulations, both RB276 and ES-12A are compatible with R12 and thus could be added without purging the system. I am told many mechanics do it. But the EPA says you can't mix refrigerants.

My preference would be to go with the RB276 if I could find someone who would sell and/or install it in a small quantity.
My second preference would be to use the ES-12A which costs about $50 for enough for probably 2 chargings plus an adapter hose. That would beat spending $100 plus a year for the R12. I haven't heard about many cars blowing up using the stuff!

As far as the EPA is concerned, their heart may be in the right place, but after the MTBE gas additive fiasco I personally think you do your own research and go from there.

Any comments from those using RB276 Freezone or Enviro-SAfe AS-12A or anything else would be appreciated.

1980 240D
252500 miles
Other than the A/C, a cream puff.

I have two cars that need to be recharged and would REALLY appreciate any info on using the EnviroSafe as a replacement. I ran out of R12 last year and dont need to spend money buying it.

Gents,

I had the same issue and converted my 190E to R-134A four years ago. I changed the drier at that time and then evacuated the system for about two hours. Recharged the system normally with R-134A and two cans of oil charge for R-134A. It's been fine since. There does seem to be some small loss of efficiency but the A/C seems to work well. At $4 / pound it's a lot more cost effective and it's readily available.

R-12 is coming down in price as the number of conversions of old systems increases (and some of the old cars die off) and demand decreases. I paid $15/12 0z. can for multiple cans last Saturday. Typically I'll use Duracool or Envirosafe (actually I mix my own propane/iso-butane...eh, close enough) as a "test" on an older car with an R-12 system. Pressure tests, leak tests, fan performance can all be checked with the HC and the system totally verified. Then I can barbeque with the HC and do the "final" charge with R-12.

john mcneil
 

What is the proper procedure [in detail] to convert my 89 420sel to 134?

Although we convert cars every week and haves done hundreds of them, I personally give the advice to leave it R12.

It confuses me the talk of having anything else be more efficient (money wise). R12 at $60 a pound is still the cheapest component (at list price) of almost all pieces of the system. The way people talk its as is this was a constant problem. Since I can't imagine someone just adding refrigerant to a leaking system, I have this problem understanding the problem.

I approach every A/C job with the concept that this is the last time it will ever be worked on. A/C units work for years. Repaired ones should do the same. The fact that R12 may be totally unavailable someday will not make that repaired A/C work any less. Today, with current availability of R12, the price of the gas charge has risen to the bottom of the component list. Freon appears to have stabilized in price and I have no problem buying it (except capital outlay).

From the experience of all these conversions I can give a few conclusions after ten years. Under most conditions the use of R134a will cause an old compressor to leak in as little as a year and probably 50% will leak by three years. New compressors will last 50-75% of previous intented life. This means some failures within a couple years and significant ones after 3-4 years. I attribute this to heat, pressure, and small efficiency loss which causes more on time.

Cars A/Cs deminish in efficiency over time. Coating occur on both heat exchangers inside and out. Unless a system is kick-axx I avoid conversion. I have had many, many people tell me their A/C was never as good before I converted them. I always believe the case is that they don't remember when their A/C performed properly and the 5% lack of efficiency is inconsequential to this condition. A mediocre A/C that is being worked on for a leak, shouldn't be converted. Fixing the leak won't make the system any better, just full. Putting 134 in will probably be noticed.

WELL STEVEBFL YOU DEFINITELY CONVINCED ME TO FIX THE LEAK AND STAY WITH R-12

Well, last summer, Steve already had me thinking hard against r134 conversions. I was at NAPA yesterday and asked their r12 price. It is 29.50 per can, and requires a 609, of course.

After I have been through converting some systems, I now wish I had left them R12. As a matter of fact, I am currently flushing the a/c in my old truck (78 Ford that I bought new,) to change BACK to r12. This is a unique case because it has a york compressor that will just not cut it at all with r134.

I am flushing EVERYTHING, replacing compressor and filter drier and charging with r12 and UV die. If a leak turns up, I don't want to be forced to waste r12 for a UV die charging. The dye will already be in there.

Changing back may be a no-no, but it's that, or change to a Sanden compressor system and spend $700 or so.

I shudder to think about converting a Benz back to R12, but I might end up doing it.

Wish me luck,

Try Autozone......R-12 ... $14.99 for 12oz. cans. Call first (few stores have it).

Wow! $14.99 per can? I never thought I would ever be excited at this price, but this is great.

I plan on getting my 609 in the next few weeks and I think I have a leak in the truck a/c. I flushed everything yesterday, replaced all o-rings using nylog on them. I suspect a leak, and I plan on finding it, fixing it and recharging. I managed to get the dye in and enough r12 to get 60 degrees at the vents. I will check it again next weekend. If it has not leaked, I will charge it the rest of the way. If it has a leak I will get out the UV light and start the next chapter of the project.

$14.99, Wow,

Good choice - good job!

Have a great day,

IMHO, the only proper way to convert a W124 from R12 to R134a is to change out the condenser to the R134a specific one, *and* change from a single aux. fan, to the double fan used in the R134a ones, as well as dryer/receiver and expansion valve. Also use only PAG oil.

We did the above to our 1988 wagon, and get's plenty cool for trips to Las Vegas.

:-) neil

I had not thought of that. The 124 was, in later years, supplied with an R134 system from the factory. This means you should be able to bolt in a condensor from one of these cars. This is the way to regain lost capacity when changing to 134.

Good tip, thanks,

The R134a specifc condenser is just half the story, you *need* to change to DUAL aux. fans for the proper airflow (don't forget the ballast resistor and a relay- almost double the current of the single aux. fan).

Also, you'll need to change the vertical bar where the horns mount as well as the powersteering cooler which takes a different route to clear the dual motors of the aux. fans.

The R134a condenser will need to have a custome hose made (about $75) due to different connectors as well as having a R134a service port installed.

I'll post pictures soon.

:-) neil
1988 360TE AMG
1993 500E

All the solutions discussed here have been R12 to R134. What about the two "alternatives" to R12 that were posted in the first post that are supposed to be 100% compatible.

I also notice they both say "vacuum system out. Dont charge under vacuum!" How does one go about not charging under vacuum? Certainly you dont relieve the vacuum with air...