It appears Maserati has an issue with this. From reading other threads you probably have a leaking heater core. If any coolant leaks out the interior front windshield takes 10-15 minutes on high heat to remove the coolant.
There are three things you can do.
1.) park it in the garage with the windows down.
2.) Go to your local GM dealer and ask for the pills you can crush up to put intot the coolant tank. This will hopefully repair the leak but it's really just a cheap patch.
3.) replace the heater core which is a day 1/2 job for a shop!!
I am constantly experiencing outside windshield fogging on my 2013 GT MC when the A/C is on. The situation persists regardless of the air flow position setting on the control unit (windshield, front/face, down-feet). Any suggestions? I am considering to replace the stock A/C control unit by the newer aftermarket AU Car digital touch screen unit. Thanks in advance for your kind assistance.