@richardlillard1 and I have chased good A/C performance for several years, because we are typically running trails twice a week, all year long. One key component that has made a big difference for me is the condenser- they become less efficient over time, and there are better designs now then those that were available in the 90's. I changed mine to a
Nissens parallel flow unit and added some electric fans. Now it regularly gets down to 43 degrees and cycles off if I'm at speed, and holds 60 degrees at an idle and low speeds- ambient temps be damned. I also run
Envirosafe refrigerant, which runs at lower pressures so it's easier on the system, and has proven to produce colder results on several vehicles I tested it on. Richard has experimented with changing out the evaporator core (same theory- degraded performance over time) as well as the condenser and also has very good A/C performance now, running 134A and a single electric fan IIRC. We both run modified fan clutches that pull more air through the condenser and radiator than the stock configuration.
@ChaseTruck /
@DSRTRDR may have something to contribute to the thread as well- I know at least one of their vehicles has excellent A/C. To be fair, in my experience that's not typical for 80s, so be prepared to work/pay for it.