passenger door lock problem

99 Jettas use an vacuum system to operate the door locks. Sometimes, in this case, there is enough pressure to active the lock but not enough to unlock. I would start looking at the passenger door jam where the rubber boot that holds the wire harness and look for cracks in the larger wire which is actually a vacuum tube. If there is no apparent cracks then either have mechanic check inside the door or behind the panel between the front and rear door. I had a similar problem that effected the locks and windows, both were not operating. I winded up needing a new wire harness which I found online at junk dealer in California. Hopefully this helps.