I guess I would still prefer manual control of heat. It is easy to find a comfort point. I believe however that when t was finally decided that under-dash or trunk-mounted air conditioning was not desirable and we wanted the ac to blow out of the same vents as the heat, things started to get complicated.

One of the most comfortable ac units I ever had was in a 1956 Chrysler. It had a HUGE squirrel cage blower in the trunk that just blew low speed cool air through vents in the rear package shelf. It cooled the car thoroughly and quickly without a draft.