If we are talking 172s here or other variants with CC, at this time of year I just hit the re-circulation button. This automatically switches on the AC and gets the temp inside the cabin as quickly as poss to the CC temp setting. In the winter time the demist function also switches on the AC but chucks out max heat also. Either way, if the AC is on the moisture disappears in next to no time. I have noticed that the 172 tends to mist up at times under normal CCs settings, especially when first setting off on a journey.