It may be because the lubricant on the window track has dried up or the window regulator is exhibiting signs of wear. All you know is that your automatic car window has developed an annoying squeak. At some point, the components that make up a car's automatic windows will age and need lubricant applied. Any lithium grease product, especially in a spray can, will quickly solve the problem.
Locate and unscrew any screws that may be keeping the door panel in place with the appropriate-size flathead or Phillips screwdriver. Screws may be hidden under the inner door handle, for example. Place the screws in a safe place where you will not lose them.
Remove the inner door panel below the squeaky window by inserting the flathead screwdriver into a crevice between the door and door panel and gently using the screwdriver as a wedge to separate the panel from the door. Once there is enough of a gap to insert your fingers between the door and the door panel, gently pull the panel away from the door. The door panel may make a popping sound as it comes free of the clips holding it to the door. Take care not to break the clips; they can become brittle and fragile over time. You also may have to lift up slightly on the panel to clear its lip from the top of the door.
Disconnect the electrical connections to the power window motor and power lock (if applicable) by squeezing the tab on one end and gently pulling the other end free. Do the same for a stereo speaker connection. Place the door panel out of your working area.
Pull the plastic water shield away from the sticky black adhesive enough to reveal the steel door frame.
Find the power window track and joints. This is the groove the automatic window slides along when it rises up and down.
Apply a small amount of lithium grease lubricant to the window track. Take care not to smear the grease on the window glass.
Turn the ignition switch to "on." Depress the small lever or button that causes the window to go up and down. Raise and lower the window three times to ensure even distribution of the lubricant.
Replace the plastic water shield and reconnect the speaker, power window motor and power lock tabs. Retrieve the door panel and place it over its original location. Align the clips correctly and press the door panel back into the clips until the panel locks in place. Screw any screws back into the door panel with the appropriate screwdriver.
If lubricant gets on the window glass, simply clean it off with a clean, dry towel.