Ok so my mother just bought a 96 A6 and the trunk won't open, I tried taking the seats out but I can't get into the trunk from inside the car and there isn't any other way in for me to open it. I can hear the vacuum pump running as I'm trying to unlock it, which makes me think that the actuator for the trunk is broken which is an easy fix provided I can get in there, any body have an idea of how to do this?

Thanks ahead of time

 

Well, if you push the lock cylinder in, it mechanically unlocks the trunk, no vacuum. I just looked at this last night. You do, however, have to make sure the security is off or it will only unlock with the remote or something like that... there's a procedure in the owners manual.

 

I've pushed in the crlinder with everything off, it still wont open

 

The lock cylinder should also have a key hole. Have you tried using the master key?
Probably your lock cylinder was left into "permanently locked" position and the central system WILL NOT unlock it.
You'll have to rotate the cylinder with the key at least 45° to the left (that will be the "lock" position), or 135° to the "open" position.

Also, you should have in the glove box a trunk remote RELEASE button, which is designed especially for situations such as this, or if the cylinder gets frozen.

 

I had this problem on the 1996 Audi A6 Quattro Sedan I bought with the trunk locked. The problem is that a plastic lever and cam on the lock cylinder break, so that the trunk will not unlock. The newer lock cylinders have redesigned plastic parts, which may be transfered to the old lock cylinder.
To get the trunk open, you need to work through the ski bag door at the middle of the rear seat. You will need some light inside the trunk. First, you need to drill a small hole in the plastic cover for the two lock keeper nuts. Next, you put a drywall, sheet metal or wood screw on the end of a long stick and screw into this hole in the cover. Next, remove the plastic cover by pulling on the stick. next put a socket on a very long extension to get to the two keeper nuts. Be sure to tape these tools together, so they don't fall apart. Once the two keeper nuts are removed, you may pop the trunk open.
You may buy a newer used lock cylinder to get the improved plastic lever, cam and switches for repairing the lock cylinder, so that you don't have to use a different key on the trunk.