I’m driving and it’s cold. I like to have air recirculate on but it turns off after a few minute and goes back to fresh. Is that because temps are too cold and the system is worried about fogging the windows?

 

It's programmed that way by Ford.

 

This was discussed a week or two ago and someone stated that the environmental system has humidity sensors that kick off the recirculate when it gets too humid...so yes, it does so to keep windows from fogging.

 

Another theory is there has been an overwhelming amount of drivers passing out from not having enough fresh air.
Okay, that is an exaggeration, however the theory is that the cabin isn't getting enough fresh air (there had to be a problem by somebody once for Ford to change it. Just like Toyota has removed floating gas pedals to prevent a floor map from inhibiting the pedal, or it becoming stuck.
Just like a McDonalds hot coffee has a warning that it is hot.