There is a post on these forums where a guy doubled up the condensers on his W126 to convert to R134 - which solved all gripes.

but - if it matters, you can make the condenser fan operate as soon as the compressor starts, you need to tap into the compressor clutch wire and make it kick start a relay that will bridge the fan trigger circuit to ground hence kick starting the fan, you can also choose to use the same relay to directly supply 12+V to the fan with some heavy wire to make it full speed.

beware - your car will sound like a jet when the fan works at full speed - it will also shorten the fans life too.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)