What are the temperatures and pressures under load? If possiblewe need the following temperatures: evap, suction line 6" before compressor. liquid line temp and condenser air in/out. I am not sure if those pressure you gave were under load or not so it is hard to say anything at the moment. It is possible the cap tube could be too restrictive, however your SCT seems awfully high. At 71psi that means your SCT is 46c. Sounds as though your condensor/fan is struggling to keep up which means the system is indeed absorbing a lot of heat. Insulating the evaporator should help quite a bit in that regard.