I am trying to understand. Did you have all of the parts that have refrigerant (freon R-12) flow through replaced? That would include the evaporator core, hoses, compressor, accumulator/dryer, condenser, and the orfice. Is that what you / the shop did? Does the car have "automatic touch climate control"? If so, the control heads can be exchanged. There is no reason you can not replace the a/c control head if it is the same part number. Are the lights flashing on the control head? If so, then there is another problem possibly happening other than the control head. Could be a mode motor. Does the a/c compressor ever go on? If not, it might be the control head or the WIRING, or engine control module (ECM) as the ECM turns on and off the compressor. To really help, try to explain clearly what is really going on and what is happening when you try to change the settings. Problem might as simple as a bad ground to the system.