Don't know if you got your answer but it sounds like your lock actuator is bad if the vacuum is working.

In the DIY section there are a couple of schematics on the vacuum system. Getting to the actuator is relatively simple. It does require taking off the door panel which is very easy to do, but needs to be done with care so that you don't break any clips. Once you get the door panel off the actuator is bolted on to the door frame and is relatively easy to get out.

Take a look in the DIY section. I don't remember the exact link but there were several drawings in there.

Good luck.