hello to all
just thought i would let you know that i converted my system over like 3 years ago, myself // i use to do ac work at a local rad shop // so i had all the tools // there was a stink before about having to change the dryer, oil, orfice tube compresser ect........... not likley, i evacuated the system, pulled the line off of the dryer, added 3 oz of the new 134A oil to the system, along with the old R12 stuff, put it together again, changed the fittings, vacummed the system, then when i got a good reading from the vaccume, i put the 134A freon in, but the secret is to read off eather the evaprater box, sometimes on the dryer, the old R12 amout of freon needed, and drop a 1/4 lb of freon.
try it you will be impressed, revving my truck at normal driveing rpm's (1500), the system will blow out 6 degrees, and i have not touched it since this year when i checked that i lost no freon over the winter.