My 85 300D sedan, I was told, has a bad compressor, won't even rotate, and my 300TD wagon, which had an r134 conversion, is blowing warm. Also, had been (and still am if still for sale) considering Holson's 300CD which needs a new compressor.

After reading some posts here I decided to look into ac - with several cars to fix it becomes worthwhile.

I think leathermang (not sure) recommended www.ackits, and has a site with a number of very useful repair processes, including ? a condenser replacement. [leathermang: can you give me your site's url? I foolishly didn't bookmark it!]

Went to ackits and ordered a guage set (R134) to start on the wagon, which hopefully just needed additional refrigerant, and the Mastercool AC manual. Later get more tools and move on to the compressor replacement in the sedan... Maybe convert to r134, change to parallel flow condenser.... Whatever.

Ok. ^&(*&^*^*^!!!!

First question - where in blazes is the high side port on a 123 with the R4 compressor? The low side port, at least apres r134 is right on top of the engine behind the radiator. Nice blue cap and snap on fitting. The illustrations from the 123 cd showing the service ports located on the compressor would seem (to me) to illustrate another compressor altogether. I can't find anything that looks like a service port. When I find it I'll probably need some sort of adapter. Can anyone help me locate the port and tell me what adapter I might need? (Since I can't find it, I can't say whether a standart r134 hi side connector was installed - that would be a nice surpise!)

Ok - 2nd question.
I though I might as well check the low side pressure, which turned out to be about 12 gpsi, which did seem low to me. Although I know it's not recommended for r134 systems without evacuating the system, I connected a can of r134 to the charging line, opened the valve, and saw the pressure rise to 50-60 gpsi. However, after 20-25 minutes (with the engine running and ac on) very little refrigerant was sucked into the system. (Can weight stayed about the same as another full can.) AC didn't start cooling. Which suggests I have some additional problems. Which knowing the hi side pressure might help diagnose...

Any thoughts and advice will be welcome. Thanks.