I would search the archives to come to a selection on this, and then check your local regs. Every shop and MB dealer I checked in SoCal told me they could not get R12 to recharge my system, and only R134a was allowed per AQMD, Cal EPA, etc.
Regarding duracool, I knew that it was not a legal product in our area, so I decided to research the reasons why. I discovered the following:
1. per the EPA http://www.epa.gov/ozone/title6/snap/hc-12a.html#q1
Duracool 12a is not legal. "It is illegal to use hydrocarbon refrigerants like HC-12aŽ and DURACOOL 12aŽ as substitutes for CFC-12 in automobile or truck air conditioning under any circumstances."
2. Duracool is hydrocarbon based, and flammable or explosive, depending on how it is used or released.
3. ANY coolant released into your car has the potential for killing you due to displacement of the cabin air, assuming you have the AC set to recirculate, and enough oxygen is displaced. Even pure nitrogen gas (which makes up over 70% of the air we breath), will kill you if it displaces the air in a confined area.
4. Unexploded or uncombusted Hydrocarbons are not generally thought to cause greenhouse effect or ozone depletion (although there is a growing body of evidence showing propane and methane as greenhouse gases). Hydrocarbons DO create photochemical smog - the brown stuff you see.
5. The only medical statement I found stating that r134a was carcinogenic was listed on a site that sold Duracool/r12a type products. No Material Safety Data Sheet, EPA, or NIOSH document which I examined listed cancer as a side effect for r134a. In fact, the MSDS documents assert that r134a tests negative for carcinogenesis by 3 different protocols. Side effects listed were frostbite and skin absorption/inhalation hazard (with potential for cardiac arrhythmia).
The EPA site above and the abbreviated site below list EPA approved (Although maybe not locally approved) refrigerants and their compositions, as well as compressor warranty info, etc. Please note that the EPA does not test for cooling efficiency, or long term mechanical friendliness to your AC system, just the health, safety, and clean air aspects of refrigerants.
Hope this info helps.
[Edited by JCE on 06-08-2001 at 06:30 PM]