SAN FRANCISCO (KGO) -- Do all the buttons in an elevator work? Sometimes it seems like the elevator door stays open forever and there is a "close door" button for just those times, but does the button work?Elevators are all around us. We get in and out of elevators constantly, which means we push elevator buttons a lot. The floor buttons light up and off we go to the floor requested, so we know those buttons work, but what about the close doors and open door buttons?I asked people getting in elevators and this one guy told me, " I don't think it does much, personally, I like to think it does, but I don't think it actually does."I checked and the "open door" buttons in person with industry insiders and we were told the open buttons always work in an elevator operating correctly.So what about the "close door" buttons. Do they work?Karen Penafiel is the executive director of the trade association National Elevator Industry Inc. Here's what she told me: "People think it is merely a placebo button and it's not."Penafiel says the buttons' function changed in 1990 when the Americans with Disability Act instituted rules giving those with mobility issues more time to get onto the elevator."The code requirements are very complex," she says, adding the rules include, "how far the elevator doors are positioned from the call button."The longer the distance between button and door, the longer the door must remain open before allowing the "close door" button to work."Once that waiting time is over, the close button will have full functionality," she says.That makes it hard for those of us just standing there to measure.