Recently on my '91 164 L I had to replace the low pressure side port (where the refrigerant is added), I only had to replace the 134A valve that was threaded onto the original schrader valve, so it wasn't a big deal. When I was ready to recharge the system I saw that 1.25 kilos was specified. So far I have only put in around 600 grams, and the pressure is around 40 psi. I haven't gone higher than that because soon after that it goes into the 'danger' zone on my gauge. When I turn the a/c on, the air is slightly cooled, but makes hardly any difference on a warm day. So my question is how much refrigerant should I add and/or to what psi should I go. Thank you!