Most days when I go out for lunch I take a shortcut through the hospital building adjoining my office. I'm not talking about obscure rat runs through wards or surgery sessions but there is a route down a series of public corridors. On one of these corridors, in one of the more remote, dark locations in the hospital (as the picture quality suggests) lives a "Ventilation Damper Panel" dashboard with a neat matrix of little indicator lights.

For three years now I've walked past this dashboard panel and for three years one of these lights, the mysterious FD33, has indicated red. It has never changed. What is it?

If it's important enough to have a presence on this (admittedly old looking) dashboard, surely it represents some critical connector or important valve or vital piece of circuitry that probably needs to be attended to? Yet it hasn't altered for all this time so, in that case, why have an indicator light for it in the first place?

So what is FD33? Is it linked to this place?