Theophilus

Yes, R134a is very definitely harmful to the environment. It doesn't attack the ozone layer, like the older refrigerants that contained chlorine, but it's still a powerful greenhouse gas that contributes to global warming. According to the New York Times (12/2/2007): "In wide use for little more than a decade, the shortcoming of R134a is revealed by a standard measurement called the Global Warming Potential, established to compare other gases with the most plentiful greenhouse gas, carbon dioxide. The warming potential of R134a refrigerant is 1,410, meaning that the release of one gram of R134a would have the same global warming effect as releasing 1,410 grams of carbon dioxide. The warming number of Freon-12, the common auto refrigerant used into the 1990s, is 8,500." So R134a isn't as bad as Freon-12, but it's still 1,410 times worse than carbon dioxide. That's why it's illegal to release it. Refrigerant recovery systems are too expensive for the home hobbyist, but you can take your car to anyplace that does AC repair work and they can take the R134a out of your system. If you get a high quote for the recovery work, shop around. They shouldn't charge you very much (if anything) because it only takes a few minutes and they get to keep the R134a that they recover. This video showing a Subaru AC system repair may be helpful:

The AC system on my 2003 Legacy Outback has been out of coolant for a long time, so I'm going to replace the receiver drier before I vacuum the whole system out. My repair manual says that I should add 10ml of refrigerant oil to the system when I put in the new receiver drier, to replace what gets taken out in the old part. Does anyone have an opinion about whether this is really necessary? As far as I can tell, refrigerant oil is only sold in bottles of around 240ml. It seems crazy that I would pay $10 for a bottle, use 1/24 of it, and throw the rest away. If people were really regularly adding 10 ml at a time, wouldn't it be sold in smaller bottles? If I really do need to add the oil, what weight do I get? AutoZone sells three different weights of PAG oil, but there's nothing in the manual or on the sticker under the hood about that. And where do I add it? Does it matter whether I squirt it into the intake or outtake hole on the receiver drier? Thanks for any guidance!