R134a pressure question

[Moose]

The only testing literature a have is from a KW diagnostic on how to test and what center temp should be given ambient temp/humidity. Those numbers in the picture were at 1400RPM, max blower, fresh air, fan on, 90deg ambient with 50% relative humidity. The center vent temp was 72deg. The coldest I can get it in similar conditions while operating the truck at lower speeds/normal is 62-65.

This is a '14 389 with a 36" sleeper without rear air. It has a two-speed Horton fan clutch. Condenser & evap cores were cleaned prior to testing. Numbers at idle were 50 low & 150ish high.

I just feel it can do way better than it is. center vent temp will rise to 70-75 deg at idle and after a few rises like that it just becomes woefully inadequate. As far as I know it is all original. What bothers me is even if I replace the TXV, compressor & switches it seems that this 389 won't do much better than this but my KW could get down to 40-45 degrees.