Originally Posted by
GraphiteGhost

Leaving the windows closed with the heat on has a tendency to remove a lot of humidity (it is always good to remove excess humidity in a vehicle, right?). OR, It'll allow the systems sensors less time to fully settle down without any outside air temperature influence (which makes more sense being it is a dual zone system with a common ductwork return).
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Yes but you didn't read the entire thread. This is to unclog a stuck duo valve not for normal heating.