Volvo: wiper, volvo 850, dc motor

Question
My question to you is early this evening while driving my volvo 850. The driver side wiper stopped working but the passenger side was still going. What is the problem?

Answer
The wipers are usually driven by one DC motor by a series of geared, moving arms underneath your dash.  Because the passenger side still works, I'd bet one of the links or arms has broken under the dash, causing the left to stop working, because clearly the motor still functions.  You'll have to get under the dash and try to figure out if and where the broken link is.  Having a helper to turn on and off the wipers while you look might be helpful.  Good luck!