My '90 Eurospec XJ-S V12 will not cool anymore. I had it recharged with 950g R134 last summer, after removing 610g. Now it seems to be the same story.The system is to my knowledge original, at least very close to original in age. There are two minute leaks according to UV-tracer. The high pressure side low pressure switch is open cirquit, to my knowldge and according to wiring diagram it is a switch and not a fuse in a '90 model.It starts to cool down if I short out the switch for some 20 - 30 secs. According to a specialist who has worked on lots of V12s it should cool from a charge of about 300g.

What is the correct info then? Does the switch cut out when approx 600g of refrigerant is still in the system? Does anybody know what pressure 600g corresponds to?




EDIT: Digging into various manuals it seems the '94 on Sanden based system takes 950g, the older system should take 1130g. But is it the R12 vs R134 that makes up the difference, or is it really a volume difference? One site indicates 10% reduction as typical which would give 1020g, not 950.