Trick question:

Dew point is the exact temperature at which the current level of humidity forms. Heat is good because it makes the air at the surface stop condensing. AC is good because it dries the air out forming the condensate in your air box. Cracking the window is generally enough warmth to interrupt the process. Most new cars have a defrost mode that turns on both heat and ac to dry the air out.

So the answer is do anything, except just turning the ac colder.