I have a one story house and I think there is a negative pressure problem. If the central a/c is on and I close the hallway door the hallway heats up like an oven. This hallway leads to all the bedrooms; there is a return air vent in the ceiling and a door in the ceiling to the attic. Obviously the heat is unpleasant but is there a bigger issue with having negative pressure like this in part of your house? What can I do to fix? There is a 2nd return air in a room on the opposite side of the house - the door to this room is usually kept open.
Many homes have only one main return located at the air handler. The separate rooms have a supply but the return is the space/gap under the room door. While closing a room door might not affect cooling too much, a hallway door cutting off a number of bedrooms would have a major effect. Installing a through vent above the hallway door might be the answer.
I love whole house fans but you have to cover them up in the attic during AC season because the vent that comes with them is not insulated and any negative pressure will suck hot air out of the attic.