awryexperiment

Guys,
Does anyone know whether the vent damper that allow outside air into the cabin is open or closed as a default when the HVAC is turned off?

I am asking because we have been having frost form on the inside of the windshield on very cold mornings. My wife always learned to turn everything off when she exits a car, so the HVAC is off while it is parked overnight. My hypothesis is that the damper is closed and the humidity within the car cannot escape and therefore condenses on the windshield.

Thanks for your input.

gk1

That is strange. FWIW I always leave mine and wife's SQ5 "on" and never had frost on inside windshield.

awryexperiment

As an experiment, we have been keeping the HVAC "on" when the car is turned off. I do not see frost inside the glass anymore.

Unless something changes, it seems like keeping the HVAC "on" at all times should solve my problem.

awryexperiment

Wanted to update this post in case some one else has this issue.

We solved the issue: the sunroof drain tubes disconnected above the headliner and were draining water directly into the car. According to the dealer, the adhesive failed. This explains the excess moisture issue.