help! MAN tgx Ventilation unit not working

Hi guys! I am new on this forum and I desperately need some help. I have recently bought an MAN tgx 400 2008 tractor unit and everything was fine with it until today. I have switched the engine and tried to put the ventilation on and set up the temperature and it wouldn’t work. When I have pressed the windows ventilation button the whole unit switched off completely and I can’t make it work. I have tried the fuse but that’s fine. Has anyone had the same or similar issues? I would appreciate if anyone can give any advice.

Many thanks

I would say that right about now you are in a Man dealer being told “won’t be long drive, have some of our crappy vending machine coffee that will take the roof of your mouth off while rotting your guts, where you can then use the scabby toilet where it would seem a bear has just had his first pony of the year after a 4 month hibernation and no we don’t have any change for the machine”