Remote central locking

[Snallbans]

Hi, I have an A8 D2 circa 2001. It was originally fitted with Vacuum central locking and infra red remote. The central locking works fine, but the remote does not work. When I looked in the Trunk / Boot for the vacuum pump it was not where it should be. There was just a pipe and nothing else. As far as I can tell it still works through vacuum but where on earth have they moved the pump to. I have asked 2 garages to try and find it but to no avail, nobody has any idea where to begin the search. The garages are not Audi specialists and the car is old so I am asking the Forum where the most likely places are for someone to have moved the vacuum pump to. As the central locking still works it is in the car somewhere but I have no idea where to start looking. Any suggestions will be warmly welcome. 

[cliffcoggin]

What an intriguing puzzle. In my experience vacuum pumps are rarely silent so I would expect you to be able to hear it, even if the noise is no help in locating it. If you can not hear it I wonder if the car has been converted to electric locking.

[Snallbans]

Thank you Cliff. I was thinking on similar lines but was unable to get a view of the driver's door lock. It is well hidden behind the steel frame. If I could access it there will be an electrical connection to either the vacuum pump or electric replacement where I could link the remote control to. I will attempt to see if I can hear some pump noise over the mechanical sounds. 

[cliffcoggin]

Another thought. You mentioned an open ended pipe in the boot. Does blowing or sucking on it produce any response at the locks? That should tell you if it is connected to anything.