Hopefully someone can shead some light on my situation.
I have a 87 190 Turbo Diesel with a rebuilt compressor and a new dryer. The system is still R-12. The problem is cooling during the day (90 + degrees) and in traffic. I borrowed some guages and these are the #'s.

About 9:00 pm the temp outside was 88F and 66% humidity. After starting the car, the highside pressure went between 250-300 and then stablized to the following.

Idling: highside 200; lowside 40 and the center vent temp 68F

Holding rpms at 1500; highside 215 and lowside fluctuated 25-30 and the center vent temp 60F.

This morning on my commute to work the temp outside was about 77F and 84% humidity and the center vent temp was 38F at 70 mph and in stop/go traffic vent temp rose to 40F.

Would the expansion valve have anything to do with the cooling efficency? It hasn't been replaced.

Any help is appreciated. Thanks!!!