Air regulator thermostat

[Eddyvdw]

I'm trying to fit the air regulator to the air-box of my 72 911E.
If i understood it well, the thermostat inside the regulator should push the valve to change the airflow from via the heat exchanger to fresh air from the motor compartment when the motor is warm. Any suggestion how to test this thermostat in the regulator? Tried already a blow dryer but no movement (valve moves freely).
Thanks,
Ed
PS: Pictures of a fitted regulator are appreciated. Bit a puzzle at the moment....