LeftieBiker wrote:there should at least be an override button,...
There is. It is the recirc button. It will permit recirc except in defrost mode, if memory serves. Running heated air in recirc is the quickest way to fog your windows up.
We just had some unusual weather in Phoenix. It rained. The morning temp was around 50° and the humidity was high. The first day I found that running in defrost mode with the A/C on and the heat off was very effective. It maintained comfort and used very little power (turn off A/C for +1 mile). The next day it was less humid and felt cooler. I found that running in def/foot mode with the heat on (77°) and A/C off worked best to maintain comfort while keeping the glass clear while consuming minimum power (turn off A/C for +1 mile). This was all in fresh mode.
I have a 15MY SV with heat pump. I try to avoid using both heat and A/C at the same time to avoid the PTC heater from turning on. This conserves power. However I still use both when windows start to fog to quickly clear them. Never use recirc when humidity is elevated.