I jsut looked into this. You can get a venture style pump for $50 from The Eastwood Company that is designed for this purpose and has fittings for R12 and R-134A. You can check Ebay for better deals on them. It works by using 90 Psi shop air. Also you need a gage set to properly do this. I got the cheap set from Autozone, now wish I got the $80 "profesional" set instead but the ones I have work.
