It's most likely the motor if the door isn't operating. It's a quick check, really. Remove the panel above your feet on the driver side to access the underside of the dash. Look for the motor, turn the key on and operate the HVAC controls for the door and watch the motor to see if the gear is turning. If not, then take the motor out and try to operate the door manually. You're probably looking at 20-30 minutes if you've never gotten up there before. Maybe 5-10 minutes if you have. It's not a bad job.
