Ranger Mods

Is it by design, that the PX3 will turn on the air conditioner when you direct air over the windscreen, even though the light on the AC button remains off and in the Climate menu, the AC indicator is off??

Mine does. Bloody annoying. Unless I crank temp about 3 deg above outside ambient temp, the windscreen gets outside condensation build up quickly and I have to use wipers to clear it. Seems an annoying "feature". Interested to confirm if others also do this.

Yes default demister. Recent humidity exacerbates the moisture on the windscreen. Easy fix, pit the windows down and demister off

That is how they work.
This is done deliberately as the AC dries the air out and as one is trying "demist" the windscreen the AC On does this far more effectively than just blowing already (potentially) humid air at it. The drier air directed at the windscreen will remove the moisture.
My works 100% even if I turn the heat up.

Personally i would like the choice of turning the AC on or off as sometimes i just want airflow from that direction but Ford in their wisdom appears to have decided the common folk don't know how to or when to use the AC to demist the windscreen.