Yep, that's a nope to the r134a in this system. I daily drove a w115 '76 240D which had a basic r134a conversion and it was never cold enough, like not even close. And I am not sure if this was due to the r134a, but I recall the rubber belt to the York compressor needing to be "bow string" tight. Otherwise, it would just slip. The York does rob noticeable power from the engine and was very noisy and had a lot of unpleasant vibrations to it.