Hopefully an easy question. I converted my system to R134A and am not sure if the required amount of R134A is the same as R12. Chassis sticker says 2.2 - 2.9 lbs of R12. Anybody have an idea of exactly how much R134A goes in? Thanks in advance.
Car is 1986 300SDL

When compared with r12, the rule of thumb is to charge 80% of the specified charge with r134.

But this is only a guide. Nobody can tell you the exact amount needed. Any refrigerant should be charged using vent temperatures and pressures as a guide.

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95 E320 Cabriolet, 159K

It is typically .85 by weight, but where the .8 comes from is that you put in .8 and then start tweaking from there. You have to be careful because the high side pressure will easily run away. After the initial charge of .8, add in very small amounts and see that the high side pressure doesn't get out of hand.

Good luck,