I live in northern Maine and in extreme cold, the flaps wouldn't remain in
the full open position.  The engine would be running way too cold that way.
The thermostat, when working, is constantly moving the flaps ... often
keeping them somewhere between shut and open.

Right now I have water cooled vanagons and once when a thermostat stuck open
(winter of course) ... the van would hardly run going down the highway until
I closed off most of the radiator with cardboard.  At least that way I could
get it home where I put in a new thermostat.

Mike

>I thought it was more simple than that.
>
> Without a thermostat in place at all, the flap will remain open, which
> is what you want once the engine is warm. The thermostat in place will
> close them when the motor is cold, and once warm, open them back up (to
> their default location when thermostat isnt in place.)
>
> I still dont see why manually flipping the air flaps closed when its
> cold for 10/15 minutes while the motor warms, then allowing them to open
> back up (their default location when thermostat isnt in place) before
> heading down the road, wouldn't work. Am I missing something in how the
> system is supposed to work when the thermostat is in place?