I have a conversion kit for R134a. However, I cannot do the conversion because I do not know which port should be used for charging. My 1989 BMW 325iS (210,000 miles, still beautiful, runs great, no major mechanical repairs, is the best car I have ever owned!) Has five (5) accessible connections into the A/C system. There are two ports on the compressor (one on the low pressure inlet; one on the high pressure outlet), one port on the outlet(?) Of the expansion valve, one port in the high pressure side supply (narrow tubing) to the evaporator (which is behind the firewall), and one port in the low pressure side supply (larger diameter tubing) to the evaporator (which is behind the firewall).
Which port should I connect the charging adapter to and, thence, charge with R134a? And how many pounds of freon is the system designed for (R12)?
Many thanks to whomever can assist. Provide an answer and I will galdly make a donation to the site.