diff lock & vac lines help

[freakytate]

a few weeks ago my diff lock packed in. light on button comes on and you can hear unit under rear seat activate.

checked vac today, started car on idle and couldn't feel any vacuum in the braided hose that purple plastic hose connects to. il split before the one way valve and check there next.

my question is..... whilst looking at inlet manifold for vac line connections i have found a white plastic thin what looks like a vacuum line not connected to anything. it terminates at rear of engine about half way up and just seems to pass the head (airbox side).

anyone know what this is for?

which vac line comes from inlet to diff lock?

[UrS4boy]

Rear Differential Lock 101

Have a read on this. The white line is most likely to the climate control head:

Lockable Rear Differential Controls, the whys/hows for the 92-94 UrS4, 95 UrS6, S2 and RS2

http://forums.quattroworld.com/s4s6/msgs/170940.phtml

[freakytate]

cheers, ive had a scan but cant find what the white line i described is for. it may sound odd but i cant see the vac signal being strong so wonder if i can test my lock solenoid with a bicycle pump or by mouth or similar. cars low and cant get my head under there

[newsh]

Can you post a pic of the white line? As Dave says, if you have AC it will prob be for the recirc valve.

If you still have any original rubber vac lines with the cotton braiding they will probably be split and leaking..

[freakytate]

i shall get a photo shortly, could see it in light last night