What is wrong with my 2003 Chevy Trailblazer

Hello, first, the exterior temperature sensing system should be repaired. Second - why did you put refrigerant in the air conditioning system in the first place, and what equipment do you have to properly test for system pressures and vacuum test for leaks of toxic refrigerant into our environment Third - what testing have you performed on the cooling system of the vehicle? Do the condenser fans run with the air conditioning on? Have you measured engine coolant temperature and checked the parameter with a diagnostic tool? There are many possible causes, and the way you figure out what is going on is by following proper test procedures using factory manuals and necessary test equipment. We can't possible enumerate here what testing should be performed.