Buick/Olds: HVAC, buick park avenue, temperature sensors

Question
My mother's 2000 Buick Park Avenue with dual automatic comfort temp now reads 136 degrees F as the external temperature (Indianapolis, Ind.)  The reading may go down to 132 degrees at 6 AM out of the sun when the correct temperature is 65 degrees.  With both sun and temperature sensors, which sensors should I start examining, is it most likely a short or open, and could it also be a problem with the system ground on the control unit?  Can the system be overridden and run in purely manual mode?  

Answer
It is probably a bad outside air temp sensor. It is located in front of the radiator. After you replace it, the car has to be driven over 30 mph for a short time for the reading to reset itself. It is the only one of the sensors that has anything to do with the temp reading on the control head.
The system is in manual mode if you dont push the auto button.