[Jim Sims]

Stormcrow is right, you really need a refrigeration harness with gages plus thermometers to fill a system correctly. That being said the installation instructions for a 1973 "factory" A/C kit specify 26 ounces of R12 refrigerant; this is the kit that had the auxilliary condensor mounted in the left rear wheel not in the front. The instructions are from Porsche but the brochure was printed by Volkswagen. Based on the 1973 factory parts catalog and a collection of parts I have that were salvaged from a wrecked 1973 911E there is also a "factory" setup with an auxilliary condenser up front behind the spoiler; I don't have the fill spec's for that system. Both systems used the big "York" compressor. I also have a set of 1976 "factory" A/C kit instructions and it also specifies 26 ounces of R12 (again it has the big York compressor) even though it doesn't have an auxulliary condenser; perhaps the engine hatch mounted condenser used in 1976 is larger or has more tube length/volume. I have them both ('73 and '76); I'll have to compare them. Not exactly what you wanted but a couple of data points netherless. Remember, don't run your system with the hatch open so there's no air flow over the condensor. Cheers, Jim