There are a few things that could be causing your 2008 Jeep Wrangler's vent selector not to work. The most likely cause is a problem with the ventilation system itself. If the vents are not opening and closing properly, they may be blocked by something like dirt or debris. Another possibility is that the actuator arm that controls the vent selector is not working correctly. This arm is connected to the ventilation system and allows you to select which vents are open or closed. If it is not working correctly, it may need to be replaced.