Cleaning vent system to kill molds etc

Exactly Easyrider. I don't worry about the smell as I clean it once a year. And my car lives in recirc only. 8 years now. If you think fresh air is helping its actually making it worse as it makes more condensate as the fresh air is much more humid than the cabin air. Compressor has to work much much harder. You don't leave the windows open in your house with the ac on do you? The compressor would be working twice as hard.
Your home lives on recirculate.

And turning it to fresh air for a while before you park is nonsense. The e box is soaked so bad it leaves a trail of water on the ground when I back out of the driveway in the morning. Would take days to dry out.

Leave it in recirc and make the car as dry and cool as you can stand it. Its easier on everything. There's alot of electronics in the cabin including the Hybrid battery.
They like it dry & cool not hot & moist. And have it cleaned at least once every 2 years.

 

Because as the incoming air temperature gets colder and colder, less moisture is removed from the outgoing air and the RELATIVE humidity rises.

When on RECIRC, the incoming and outgoing air is basically the same and the relative humidity gradually creeps up.
Another factor is that less of the inside air is expelled because of the recirc.
Odors AND moisture just accumulates inside but it does get colder quicker.