This sticking regulator valve sounds like it could be the problem to me. While watching the heater core and evap temps on the display the all seem to read about the same temp, and today its about 78 or so out and the pressure would drop to about 6 bar while cruising and the evap/heater core temps would show about 67-68, so it appears it is doing a little bit of cooling, but just not much. As soon as I would downshift it to pass or something like that, pressure would rise up to 12-14 bar and evap temp drop to 37 or so.

Is the fix for this a replacement compressor or is the valve a separate part that can be replaced?