I'm considering a recovery of the R134a from my '75 GMC pickup so that I can check out the old evaporator for leaks (original; might have a small leak), replace the orifice and accumulator, check hose connections, and then do a complete recharge. I may also make new hoses, in an attempt to improve the routing and make it easier to work on the engine. The A/C is currently working, but has gradually lost some charge over the last couple of years, so its cooling is not very effective.
If I buy a recovery machine and tank, what do you do with the R134a that is recovered? Is there somewhere you take it for disposal, or is the assumption that you could filter it and use it to refill the system?
FYI - I live in Northern Virginia, where its difficult to find a small shop that has experienced mechanics and wants to bother with working on an old A/C system. They have plenty of business from newer vehicles where they can hook up an automated machine and let it do all the work.