Chrysler Repair: 1999 Concorde, air distribution system, diagnostic capability

Question
My 1999 Concorde AC/Heating blower doesn't work, a technician already test it and said it works with direct connections, the problem looks it is on the temperature control, I already test two USED ones, but didn't work, the guy on the wrecking parts said could be the system are blowing it. How can I be sure where the problem is or how can avoid the problem before buy a new expensive temp control?

Answer
Hi Dimas,
The atc unit has self-diagnostic capability. Here is the way I have told others to check out for a fault code that may be hint as to what is wrong:
"Before concluding a new panel is needed a test should be done to see if the computer has recognized any problems and described them in the form of two digit fault codes stored in its memory. Did someone do such a inquiry? If so, what numbers did they get? If not you can do the readout yourself:
The unit does have a self-diagnostic capability. Set the temp to 75<sno. The engine has to be running and the car not in motion to do the test. Simultaneously press the floor, mix, and defrost buttons, (the 1st,2nd and 4th on the top row) and see if the display unit begins to blink. Release the buttons when it has started to do that and then after it blinks for a while longer watch for two digit numbers to appear on the readout. Those are the fault codes. If the first number appears and stays in place, push on the first button in the bottom row (panel) to continue the readout. At the end of the readout the unit will return to normal settings.
Then write back with the number(s) and also tell me more about exactly what is wrong with the function of the unit.*
I would do a thorough readout before buying a new control unit. It may be a part in the air distribution system itself rather than the computer that is the problem."
Roland
PS May I ask a favor? Please use the 'thank/rate' tab below to offer me a nomination to be the 'expert of the month' which I am in competition for this month. Just answer 'yes' to that question.
You also will find a space for any coments to tell me what code numbers you got, and you won't have to wait for me to be 'available' to take a question. I will respond that way.
*The code numbers range from 23-51. You can also get a decoder list at www.allpar.com/fix/codes_climate.html