1993 945 with R134a, ambient temp = 100 F.(sitting outside in sun) low side pressure = 110# (compressor not engaged) then down to 50# with compressor running for 10 minutes, vent temp 80 F. This operating pressure seems high to me compared to my '93 945T that was running 38#, sitting in shade in garage and much lower vent temp (around 60 F.). I bled out some refrigerant (on car #1) until the pressure dropped to 40#, but the vent temp went up to 82 F., so I added back 134a to 50# and the vent temp dropped to 78 F. I can't seem to find the high side connector, so wasn't able to hook up the high pressure side of the gauges.

Is this pressure too high? If so, why would the vent temp be 78 F.? I checked the heater flow valve and confirmed that it was shutting off, and also clamped the hose between the valve & firewall to make sure. Air flow through the vents seems adequate so I didn't think the evaporator would be plugged. Plenum actuators seem to be working ok when I move the switch from vent to floor and back.
Marlin