2003 Chevy trailblazer ltz 4.3 six cylinder. I have replaced the ambient temp sensor. Question = I replaced my ambient temp sensor because my heating/ cooling unit would take for ever to change from the temp in the garage to the temp outside.

After the replacement the temp readout still takes forever to change, do I have to do a recalibration?

Answer: Usually, the ambient temperature sensor requires no recalibration. It will adjust on it's own after driving. The same goes for the actual temperature change you see on the dash. The normal operation of the sensor is to either show the last temperature it was reading, or the current temperature once the vehicle is started. This depends on how long the vehicle has sat without running or being driven. If you have an Automatic HVAC system, you can reset the display manually by turning the ignition on, and then simultaneously pressing the MODE, FRONT DEFROST and REAR DEFROST switches. Otherwise, it will reset to the actual ambient temperature after you've driven a little bit. This is usually highway speed for a few miles, so that's why it may take your vehicle a bit longer to display it if you're just driving short distances or around town.