Sorry, I should've been more explicit.
It's a 2005, with the digital climate.
I've seen others that operate the way your Acura does. On the OBW, the default is to control each side with sepreate nobs. Nothing in the manual about controlling them in tandem, or a way to switch to that mode.
I'd guess there's a hidden mode, but I haven't been able to find it by trying various button combos.