FWIW, I drive the same route every morning, and every morning my car switches from EV to HEV mode at almost exactly the same place. And that place is almost exactly 26 miles from my house.
It really doesn't seem to matter much whether my climate control is on or not, I pretty much always get exactly 26 miles, give or take 1 mile. I've never gotten only 24 miles on a charge.
That said, I haven't used the AC much yet, and I expect that when I do have the AC on full-blast this summer, it'll drop the EV range by a couple miles, because the AC compressor is electric-powered.
I would bet that Kia noted that the AC reduces the range by 2 miles, and for simplicity they just applied that offset to the calculated range whenever any of the climate control (AC, or fan, or heater) is on, rather than only when the AC is on, which would be more accurate.