I have a 1999 pontiac montana. the passenger side window will not go up or down.

Check the fuse first but, I suspect it will be the motor for the window that needs replaced.

I have the same vehicle same year and I concluded after testing and double testing both window motors are out on my van. (temporary fix) I was able to take the panel off disconnecting the windows from the tracks so that I could block the window from coming down. it gets pretty cold on this side of the country. it started with the driver side window not being able to roll up except when I would smack the door or shutting the door hard. then the passenger side went out,the same problem diagnosed it ended up being the motors froze up on both sides.