Richard, did I understand you to say that you were going to mix r-12 and r-134 in the same system?? You could be asking for bigger problems by topping up an r-12 system with r-134. If you are going to use r-134 there are a lot of other things you would have to do before making the switch to the other refrigerant. It's not a simple drop and swap operation. There a a number of other posts about this topic. Do a search, and beware of easy quick fixes..

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Jeff L
1987 300e
1989 300e
1987 BMW 325

[This message has been edited by jeffsr (edited 04-09-2000).]