HVAC switching from recirculate to fresh automatically

2011 Tundra
My HVAC will switch from recirculate to fresh air automatically from time to time.
Even if I set it to one setting, it will switch. Not immediately but randomly.
Anyone know if this is normal? Any way to stop it?

 

2009 here with same issue but no answer for you. Bill

 

IIRC, this is the default operation. Under predetermined conditions (temperature outside, etc.) the computer will change the operation of the recirc damper. If you have a bi-directional scan tool or Techstream there is a setting under the customization menu that enables you to change to a manual operation of the damper control.

 

Thanks for the reply.
It's not that big of a deal for me to have it changed. It's just a PIA at times.

Tim