When you set "defrost" (air to inside windshield) in my 2004 Celica GT, you also turn on the A/C--no choice.
My question is---is there a compelling reason to use the "fresh air" setting when using "defrost". It is actually written on the console panel next to the "defrost" knob.
Is reads, "When using defrost, use fresh air". Not in so many words, but in symbolic langauge. My question is Why? Will something bad happen when you use "recirc"? Will moisture build up behind the dash or something?