I've had just the opposite problem with our 97' GCV. (3.3L, 4spd)
The front A/C is almost 10 degrees warmer than the rear. (55 discharge in front/ 45 discharge in rear) I've ruled it down to the blend door. I've been living with it for about 6 years now.... Until I need to remove everything down to the firewall on this ole' girl to do an evap coil or heater coil too I'm not going there.
I can't tell you much about the rear A/C though. Sorry.
But, if you ever need to replace the front expansion valve (& plugs, wires + many other things) then you need to remove the hood, windshield wiper motor gear/linkage and the intake manifold parts.
Are you sure about the refrigerant level? Did you recover/evacuate/pressure test and then weigh in the factory recommended charge first (yet)? This is a single compressor system with two evaporator coils. The charge is critical.... I wouldn't worry about the oil level initially unless you know theres a leak and see alot of evidence that the oil was leaking out with it too....
Maybe this'll help for the next job? Good Luck! Keep us posted!
