I just noticed the white hose going to it is completely rotted and broken. I know it has to do with heat and cooling but not sure when it actuates or why?

1992 F150

Thanks!

 

that looks like the vacuum controlled HVAC Recirculation Door Actuator

 

Thanks. I have tried wiring it in the opposite direction and the only thing I can tell is it might effect Max A/C position that I never use.
Just trying to figure out why my air is not as cold all of a sudden. Maybe because the system is 24 years old and all original!

 

I believe it just changes the door position from outside air to recirculating the inside air. Being old should not be too bad. As long as the a/c is charged up properly, check for dirty coils possibly.