Been thinkin'...we had to switch from R12 to R134 because the R12 was causing a hole in the ozone above the South Pole. Now, if I want to work on my A/C system I'm still required to have the R134 recovered rather than just vent it to (the South Pole?). Can anyone tell me why we went from R12 to a less efficient but just as lethal (to penguins) R134? What does it cost to have the system "recovered" and do they use it again?