I vote for a bad switch in the door.

I have been told, and have found, that Volvo switches are a weak link in some circuits.

If you can pull the switch assembly out, use a meter to find out which wire provides power - then you can use a jumper wire to send power to the other leads to see what happens.

If everything works, you can determine that the switch is bad. In older cars, you can take the switch apart and clean it - see the 700/900 FAQ to see how to refurbish window switches - I have done several.

Many Volvo items can be pried out with a small screwdriver - these items have a hook on one side or end, and a detent on the other side or end.

If you try to pry the hook end, you will break it!

I would try to pry gently on one end - if that does not work, try the other end. If the ends do not work, try the sides.

Perhaps someone will tell you where to pry