Hi, Ther's already a ton of messages about conversions R12 - R134 (see http://www.imperialclub.com/Repair/Air/refit.htm) so i don't need an advise or "if it works" but just a fact: what should be the filling charge with R134 if my '57 FSM says 3 pounds (of R12) ? I've charge the system with 134 (yes, i've change oil with lot of problem: need to remove the V2 compressor oil sump and had after a lot of leaks with "home made" gasket. Bought one new from CollectorsAutoSupply, no leaks now .. I've also put correct fittings, new drier and .. that's all !). I've put around 2 1/4 pounds (someone said that you must charge to 75 - 80 % of the old R12 charge), the system works but the air is not very cold, just refreshed... Not sure if the system will last long (rubber hoses ?) but the "red necks" at meeting are on their as.. when i say "yes, in 1957, US cars had A/C and it still works .." In France we've now A/C cars, yes, since .. 10 or 15 years !!! So when you say that a fifty years car have AC they don't believe you (until they see the compressor..) I also understand why convertibles have been "killed" by A/C. Today, 90° F (very hot for France !), driving in town, so i kept my (soft)top up and put A/C on ... -- Philippe COURANT (Pau, France)- Webmaster des sites ACCF et C-I-F Imperial 1957 Crown convertible Buick 1996 Roadmaster wagon - American Car Club de France (ACCF) : http://www.accf.com - Chrysler Imperial France (C-I-F) : http://www.ifrance.com/c-i-f - Cadillac " Standard of Excellence " : http://www.ifrance.com/accf-cad - SportsCars : http://www.ifrance.com/accf-sprtcar