Either of those ideas sounds fine to me.Do you think it's worth shutting the AC vent and keeping the windows open during the day to help them get used to it? Or maybe increasing the temperature a few degrees every day? Or would that just cause them needless stress/panting?
Or should I introduce them to the coop by taking them out there a few hours more each day (then back to the AC afterward) until they're out there all day?
You could also combine them: block the AC vent in their room, and also take them outside each day.