The thing this morning was: after driving the 20miles to work with the heaters on (it was 1oC), discovered that after turning off the ignition, the cooling fan did not turn off and instead got faster and higher pitched.
I turned the ignition back on, the fan subsided, then after a second or two kicked in again. Turning the ignition off, and the fan got even louder, as before.
I eventually turned on the ignition, pressed some of the a/c circular ventilation buttons several times, then turned off the ignition, and it finally shut down properly.
Related to this (maybe) is the fact that despite having never used the A/C since I bought the car, I find that when I turn on some of the other heating features, the A/C turns itself on! Some days i can just start the ignition and the A/C turns itself on.
These things definitely seem related - A/C that seems to be on by default, and fans that don't know when they're supposed to be on or off.
The car is still within warranty, but I'd just like to pick your collective brains before I take it in. Is there a known fault I can point the Ford mechanics to directly? I don't want to risk the mechanics not-finding the problem and charging me.