Need advice on making homemade grille shutters / door
 

I plan to have a full grille block on my 1993 Civic, but will have an area that opens once the engine fan turns on.
I would think it pretty straight forward to make work.
I'm guessing that i could use the electrical signal that turns on the fan to also open the door on the grille block.
Once the engine cools and the fan goes off, the loss of the signal would make the door snap shut again.

I was into R/C planes as a kid, but was poor, so I never actually had one.
I remember little motors used in R/C planes that are called servos.

Could a servo be used for this ?

The idea is inspired by what 'AndrewJ'.did with his car decades ago.
His design turned on a light and alerted him to pull a cable controlled door in the grille.
Brilliant and simple, but I'd like too see if I could make it be controlled by a motor instead.

...vs
You say an apple, I say a napple.

mechanism
 

You might want t look at an 'escapement' mechanism, as used in mechanical clocks.
* Your air 'door' could be subjected to constant, door-opening, 'return-spring' tension, tending to keep the door open.( fail-safe )
* When the radiator temp sensor triggers voltage to the cooling fan, voltage would also be enabled to an escapement dog solenoid, releasing the dog from it's normally- extended position, allowing the return spring to pull the door wide open.
* The 'dog' releases the escapement gear, the return-spring pulls the door open, while the cooling fan operates.
* When cooling is satisfied, and the radiator thermal switch goes open-circuit, killing the cooling fan, the solenoid which engaged the dog to the gear would go 'dead' and the spring-loaded solenoid would extend the dog, capturing every tooth of the gear while the motor ratchets the door back closed.
* The door motor does not have to run 'forwards' and 'reverse.' Only 'forwards.'
* 'Opening' is just a passive function, because of the return spring.