Central lock not working after "hiss"
 

Hello all.

I posted this on the diesel discussion, too, but since then it's been buried by so many other posts I'm afraikd no one will see it.

To make a long story short - while fiddling with the key in the driver's side front door I heard a hissing sound that lasted a few seconds, and my central locking stopped working after that. I took the door apart thinking maybe I'd disconnectded a hose or something but that's not the case. Can anyone tell me where the vacuum switch and the control valve are? Or am I even in the right ballpark thinking the valve could be the problem? I've had trouble finding info. so far.

Thanks