We also call it the defroster.
The BCM doesn’t turn the cabin fan on on cold start in freezing weather if the ATC is in “Auto” mode until coolant temperature is above some threshold. Makes sense since it won’t accomplish anything except create a cold draft for you and your passengers.
You can force the ATC out of Auto mode by moving the fan speed button, at which point the fan will spring to life to whatever speed you select. (I’m thinking also pushing any button that forces the system out of Auto mode will accomplish the same thing.) But again, until engine temp. comes up, it won’t accomplish anything good.
Another fact not directly related to your question is that the defrost mode can be useless in removing condensation/fog/mist from the windshield in humid situations if the a.c. is not working. The a.c. is run even in cold temperatures to condense out the moisture in the air before it is sent thru the heater core and out the vents. Without the a.c. to pre-dry the air, the moisture will condense out on the windshield and windows making it impossible to see. If you’ve ever had your a.c. out of order in a humid area, you know what I’m talking about.
'98 LXi - Later Concorde gages (black w/ chrome rings)/'99 LX - LHS gages (white) - HIR bulbs