I've read some more posts and it seems people are split 50/50 about whether converting to R134a buggers up your system.

can you re-charge with R12 after a R134a conversion or is it a no-going back deal?

my tech says the conversion isn't the reason the charge isn't holding, and I usually trust him, but I'm interested in whether the quick conversion he did could be the problem?

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1993 320TE M104
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past:

1983 230E W123 M102
1994 E300D S124 OM606 (x2)
1967 250SE W108 M129
1972 280se 3.5 W108 M116
1980 280SE W116 M110
1980 350SE W116 M116
1992 300E W124 M103
1994 E280 W124 M104
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"music and women I cannot but give way to, whatever my business" -Pepys