2002 Chevy Trailblazer

Air Conditioning problem
2002 Chevy Trailblazer 6 cyl Wheel Drive Type unknown Automatic 95000 miles

My exterior thermostat reads the outside temp. Most often times wrong. Sometimes it says that the outside temp is -35 degrees which is impossible given that I live in Florida. When this happens, it's impossible to get my Chevy Trailblazer's a/c to work properly.