> Nothing you've said indicates why the button does nothing.

Let me expound a bit —

The close-door button cannot override the ADA minimum 3-second open time… the door must remain open for at least 3 seconds no matter what you press. But, most are configured to automatically close at 3 seconds. So as soon as the door-close function is no longer overridden, the door starts closing anyway, so pressing the button has no effect. With the door-open button and door sensor, they generally start closing immediately when they’re not active, so since the doors are already closing, the door-close button has no effect. If the door-open button is configured to open the door more than momentarily, the door close button should function.

If the elevator is designed to stay open longer than the 3-second period during which the door-close button is overridden, it will be available after the first 3 seconds. So if it’s configured to stay open for 10 seconds, the door-close button will be inactive for 3 seconds, but will start a door close, when pressed, from the 4th through the 10th second. At 10 seconds, the door will be closing anyway.

If a regular people-moving elevator is configured to be capable of closing the door in less than 3 seconds, it’s out-of-code. Since professional elevator companies maintain and configure most (all?) up-to-code elevators, and they’re probably liable for them to some extent, I doubt that’s common. It’s not like I’ve studied it or anything though.

I’m pretty sure that timing it out with a stopwatch would reveal that no matter what is happening, the door stays open for a minimum of 3 seconds. Anything beyond 3 seconds depends on how it’s configured, but most are configured to close as soon as they legally can.