Should interior doors be left open or closed to circulate air properly or evenly throughout a home cooled by a central AC unit?

Closing interior doors disrupts and blocks return airflow, and many older homes do not have vents in hallways, so shutting doors makes rooms chilly and hallways uncomfortable. In addition to keeping doors open, you might want to consider placing small or medium-sized fans in strategic locations in your home. It's a good way to keep the air moving and to redistribute it from cold areas of the house to warm ones.