Ok now bear with me - I have a memory of seeing two different illustrations. Neither may be from this site
but perhaps...
One was an illustration of various ways to put your heater (or it could have been AC) controls to do different things like defrost, fan on w/ heat, fan on no heat, etc. I recall seeing the control levers at different places along their plane of operation and a brief explanation of what that was used for.
The other illustration I recall was showing how to open your vent windows and your fresh air vents to show air flow - or something along those lines.
Has anyone else seen these illustrations before and have a copy?
Thanks!