It is difficult to know what's going on with the refrigeration portion without pressure readings. Assuming the system is indeed fully charged, a faulty temp control system inside the car could be the culprit.

I'm not sure exactly how it works on your 201 chassis, but in one way or another it probably modulates coolant flow through the heater core. If this portion is not working right the system could be perfectly charged, but still not cool well.

Good luck,