Introduction: Is the AC/Heater Running?
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About: I am an author and a maker. My current project is Santa's Shop. I'm working on a science fiction type book--more later. @EngineerRigsby
If you want a visual clue that your cooling/heating system is blowing air, just add a fan to a vent.
Print the 3d files from:
http://www.thingiverse.com/thing:479302
Insert a pin into the base, then screw the base onto a vent using the vent's side screw. Rest the printed fan blade on the pin head and the thing will spin like crazy when air is moving through the duct.
