A car window that will not move rarely means the glass has failed. In most cases the fault sits inside the door, in a part the driver never sees. That gap between what looks wrong and what is wrong drives many poor choices about car window repair. Drivers buy the wrong part or leave a door open to the weather. Advice on the subject passes from friend to friend and gets worse on the way. This guide tests seven common beliefs against how power windows actually work. Each myth i