You are most likely to find a switch labeled “fan switch” in your pantry. This switch is considered a 2-pull switch and uses low voltage wiring to communicate to your furnace and makeup air unit to turn on and off. This could be used in order to help bring in fresh air once the fans in your home exhausts air out from cooking or from the washroom. This system keeps your air fresh and keeps positive air pressure in your home.
-2nd Year Electrical Apprentice, Alex