My Volvo has 3 recirculating modes. OFF, ON auto in which every once in a a while it brings in fresh air then goes back to recirc mode, and ON manual for recirc on 100% of the time.

 

I read somewhere, maybe in my other car(MB) that the air re-circulation shuts off after certain time to prevent the air in the cabin to be too impregnated with CO2 from the occupants, what can cause sleepness therefore be dangerous.

 

It’s 78° in houston today and I have a/c going with recirc on. It has stayed on for some time now. It must be tied to outside ambient air temp. 🤷🏻‍♂️

I wish there was a Ford tech that could chime in.

 

Or when a Powerstroke 6.0 is nearby

 

exactly

 

An update to my post, went for a 15 min drive today and upon getting in the truck I pressed and held the recirc button for 3-4 seconds.......it did not not turn off on its own after doing this, so hoping that is a fix for me.

 

The system will switch to recirc automatically when the temperature goes above a certain point, it cools more efficiently on recirc when the ambient air temp is higher. My Toyota Camry does the same thing.

 

This may be the worst thing about the truck. I have called my local dealer he told me that it seems to be a humidity sensor. I have a XLT 302a and have not been able to find anything about this. So far it really only seems to be trying to kill me (too many turds are "rolling coal" in Houston).

 

Interesting.

My 2018 F150 Lariat does not turn recirc off or on automatically. It stays where I set it and in fact will be in same mode when I turn off and exit truck and return, restart.

 

Right . Our 99 Freightliner Semi does the same thing. After 20 minutes it beeps at you and tells you that the air air conditioning setting is still in Recirc and it's stale air now, switch to fresh air setting.

Fogging windows is the next problem. When vehicles were first invented they tried adding heaters that didn't have any fresh air coming in and the windows would fog up from the moisture you are putting out when you breathe. On the AC setting that wouldn't be the same problem though.

Freeze up would be another problem. The evaporator could freeze over if you are recirculating to much all cold air.

I rarely ever run on re-circulation.

Why are you running the AC when it's 45 to 65 degrees outside anyway ??? Spinning that AC compressor takes power and gasoline. Wears it out quicker too.

Though I doubt the compressor is actually running.. In the old days there was a little temperature sensitive snap switch wired into the compressor hot wire that would open when it was to cold and not allow the compressor to run. That's all probably computerized by now.