also, be surre surre surre that you have totally blown and flushed all traces of mineral oil from the evaporator, condenser and all freon lines. also replace the expansion valve and reciever/drier. now, once you have done all that, buy some real R12 and put it back the way it was. don't cheap out, 134a is junk in this system. it will not cool well, it will kill the compressor. just go back with 12.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!