It's annoying, isn't it? My old 106 could either have cold, fresh air or centre-of-the-sun-hot air depending on the settings of the heater controls. I think if you put it on feet and screen, they went warm and the centre vent went cold. Of you put it on vent with the heat on, then heat came from the centre vent - and that could melt your face off within a mile on a frosty morning.

I think some BMWs have a switch to change between cold or warmed air on the centre vents.