Junkman

It has been a while since I have looked at this thread, so I will respond on some of the older posts with comments interspersed, but not in the order that they were posted.





No, it isn't inexpensive, but the labor involved is the greater expense, even if you are doing it yourself. If you think that your time is free, then consider what you might be doing with those hours, if you weren't fixing your air conditioner for the 2nd, or 3rd or more time.


I have no idea what R12A actually is, and once you install it, you will have "contaminated" the entire system with this "new" refrigerant. I have a strong suspicion that it might be one of the newer propane derivative gasses. If for any reason you need to service the system, once you use a gas that isn't widely accepted, no one will be willing to collect this gas, and you will have no choice but to vent it to the atmosphere. I did read the manufacturers statements as to it meeting the UN Montreal Protocol, and the statement ....



I strongly recommend that you use a good quality air conditioning flush, noting that items such as mufflers, receiver drier, and the compressor, cannot be flushed. Flushing is specifically recommended for the evaporator, condenser, and straight through hoses. I wouldn't use a stop leak, since it is more than likely it will gum up the system and cause you more problems than it might cure. A properly serviced system should be tight enough to hold a vacuum and a pressure test prior to installing the refrigerant.


Having owned a number of Mercedes, I can say first hand that just because the Germans used a product that doesn't mean that it is a good product. I owned a 1995 E320, which has a wire harness that was "biodegradable", and it started cracking and shorting out wires before it was out of warranty. Mercedes solution at the time was to individually wrap every wire under the hood. At that time, they had no other solution for the problem. That solution lasted long enough for the car to be out of warranty, but failed shortly there after. Mercedes refused to replace the wire harness, and said that it was a maintenance item. They said the same thing when the rubber air conditioning hoses failed.


Stick with good quality used GM or NOS, and forget about trying to retrofit R134A into a system that wasn't designed for that gas. I believe that this is why GM/Ford/Chrysler/etc. never manufactured retrofit kits for use in their cars of previous years.




This is an indication that the system had previously serviced, and improperly evacuated, and was contaminated with moisture. Some shops don't use virgin refrigerant, and install the refrigerant that they have collected from doing evacuations. It could also be a result of cross contamination of refrigerant oils. It would take an oil analyst to determine the exact cause. This is the reasoning behind flushing an old system that you have no history of its past service life.


The quality of the materials in some of the reproduction air conditioning condensers and evaporators is no where the quality of the original GM parts. Find NOS whenever you can, and they will always out perform the reproductions.



If you are planning on returning to R12 at some time in the future, start collecting all the necessary part now, since they are going to get harder to find in the future. In many instances getting the R134A fittings off of the R12 fittings is going to be difficult, if not impossible. Originally, they had barbs that would dig into the original threads if you tried to remove them. I have been told that the newer ones don't have this feature, but never having done a conversion in recent years, I can't say for sure. After having done a few conversions from R12 to R134A, with mediocre success of sufficient cooling, I realized that the savings of R134A wasn't worth the extra work to put it back to R12 when someone was dissatisfied with the cooling of the system. A system that was designed for R12 will always work better than trying to retrofit a R134A system into it. To me, it is like trying to adapt a Ford part to fit a GM car. It can be done, but at what cost?????

Olds64

Thanks for the input. I've been doing some browsing and apparently there are even folks out there that use difluoroethane from computer air dusters to recharge their AC:


To me this seems a bit like jury rigging an AC system. While I might be willing to use r12a or freeze 12 to recharge my AC system, I don't think I would be willing to use this trick. Thoughts?

71Convertible

I've only done one A/C conversion and it was on my 1971 Cutlass Supreme convertible. I did this about 4 years ago when I had the entire power train out of the car. I'd previously done seal replacements on the older GM R12 compressors. That and availability/cost of R12, I felt it was time to move away from that compressor design. I replaced all of the R12 components with R134 components. My Cutlass isn't a show car so I wasn't concerned with the different look in the compressor; though I did save the original R12 compressor and mounts if I or someone else wanted that all put back. In the warm, humid coastal Virginia climate, I find that the R134 cools very well. I run the A/C on hot humid or rainy days when it's not comfortable to have the top down.

Olds64

Don, you mentioned that you installed r134a components. Did you just install a Vintage Air system or did you replace pieces individually so you could run r134a?

71Convertible

In 2012, I purchased and installed items from Classic Auto Air, Tampa, FL. for my 1971 Cutlass Supreme convertible. This included the replacement compressor with mounting bracket, POA valve, condenser, dryer, evaporator and all hoses. They were good to work with and quickly resolved the only issue that I encountered with the parts I purchased. I decided there was enough corrosion/oxidation on the 41 year old condenser and evaporator that I would bite the bullet and replace it all when I had the engine out of the car for rebuild. Here is a picture from today, showing some of the components.

zeeke

And you missed the biggest reason of all R12 is dichlorodifluoromethane which has no upper or lower explosive limit and propane is dimethylmethane which is a completely different chemical with different carbon bonds and has a UEL of 9.5% and an LEL of 2.1%. In other words R12 is not Propane. Another point to mention, with propane, the flame cannot travel into the lines due to the lack of oxygen so it can only burn in the vapor space which needs to be between 2.1% and 9.5%. To rich or lean it will not burn.

What we see in the movies with gas tanks on cars exploding doesn't happen, they rupture with a sudden rush. Just like that propane video. I've been to hundreds of car fires and have never once seen the violent explosions portrayed in Hollywood, however a propane tank can BLEVEI which will cause a much more violent rush.

The violent flame you see from R12 freon is most likely caused by the gas escaping and creating a vortex introducing more oxygen to an already burning fire.

The reason R12 was no longer manufactured is the damage it does to the ozone which protects us from the sun. R134a was its replacement.