Have been watching your posts about your problem. Surprise!! You don't have
a problem, I think. What happens is that when you have the climate control
system off, the main vent flap opens to allow fresh air into the cabin. When
the climate control system is on, either heat or AC, that flap is closed
either entirely or partially (depending on the system requirements). This
function is attributed to a government requirement that is supposed to
prevent any buildup of carbon monoxide gases in the passenger compartment. I
think it's BS on my diesel, plus I don't appreciate 100+ degree air during
the summer coming into the car, so I cut the green line behind the glove box
and plugged it off. Now that flap is closed all the time.
On mine, when the AC is on, I think it's supposed to mix about 20% outside
air. Not sure the precentage with heat. Anyway, I don't want hot air coming
in during the summer nor cold air during the winter.
In the back yard, warmly under the oak.