During the recent cold snap in the UK, I tried to select direct heat to my feet and unfortunately the system just blew cold air no matter what I did.
I did get warm air from the middle face vents, but it took a couple of miles for this to happen.
I subsequently checked the coolant levels in the two tanks and discovered that the main tank (larger one was about a litre short of fluid).
Topping this tank to the correct level appears to have fixed the problem. However, the problem may be due to a system requiring a “bleed”. If this is the cause you should take it to the dealer.
However trawling the internet, brought this document to light on the Forum……