As you will note if you read my most I immediately eliminated the PIR method for that reason.
Before I actually try this I will do some learning to get a feel for the platform.
Basically I envision a platform about 12" dia and about 1.5 to 2" tall on which any suitable table fan would sit.
My initial thought is to use perhaps 5 IR sensors/lenses arranged with one in the center position where the fan will "aim" with two on each side spaced to permit them to see a fairly wide area.
If I use a PIR for anything it might be as an occupancy sensor to simply turn the fan on when I enter the room and off again after I leave.
I found a few discussions on solar panel tracking. I need only one axis of course. When I get to the point of experimenting I may need some help learning how to program to tell Arduino to try to look at 5 inputs and aim to put the IR transmitter in the center detector. I have a pretty good idea what I need it to do but not yet how to get to that point.
I will follow up on this here later after I get my first Arduino on Monday and have a bit of time to learn about the hardware and software.
Have a great day !