I am interested in turning on a small fan as a booster to an oven cooling system. I want to control the fan on/off with either an air flow switch or a temperature switch. The oven has a cooling fan already. It also has a flap that opens when the oven starts to cool. The oven fan blows hot air out thru one opening to cool the oven. It also draws cool room air in thru another flap. Then the flaps close.

I would like to add a fan at the inlet of this flap to cool the oven even faster. I only want my booster fan to run when the oven flap is open and the oven is cooling down. My first idea was to turn the fan on by detecting air flow out the oven flap. Or i could also use the hot oven air and a temp switch to turn the fan on and off.

Any ideas for switches for either idea? I will need to make about ten of these.

I don't want to run the booster fan all the time. The main fan does. The other thing i was thinking was to tap into the flap power because they open when the oven needs to cool. However, the flaps are run by a stepper motor and I'm don't think I'll be able to use that power source.
Thanks.

There are 6 wires to the stepper motor. It would be great if i could power a dc fan from there. The fan should only turn on when the stepper opens the flaps, then turn off when they close. Is this possible at all? The wire decriptions are in the attached doc.
Thanks.