Hi, Love the course and examples.  It is obvious you put a lot of time and effort into this course.  Thank you.
 
In the test for Celsius or NOT Celsius (lines 38 – 46), on line 44 you inadvertently use TEMP_THRES_MIN (again) instead of TEMP_THRES_MAX.  Making this correction the sketch compiles correctly.
 
Thanks again
 
Hank