* Broken or dislodged window regulator: This is the most common culprit. The regulator is the mechanism that moves the window up and down. Over time, the cables can break, the plastic components can crack or wear out, or the regulator can become detached from the window. You'll need to inspect the regulator mechanism to see if any of these issues are present. This usually requires removing the door panel.
* Binding window: Something might be obstructing the window's travel. Check for debris, damage to the window itself (a crack that's binding), or even a problem with the window felt (the weatherstripping).
* Window tracks: The window slides in tracks within the door. These tracks can become dirty, damaged, or misaligned, preventing smooth movement. Cleaning and lubricating the tracks might solve the issue.
* Wiring issue within the door: While you've checked the switch and motor, there's still the possibility of a broken wire within the door harness. These wires are subject to wear and tear from the door opening and closing. A visual inspection of the wiring is needed, paying close attention to areas where the wires bend and flex.
Troubleshooting Steps:
1. Remove the door panel: This gives you access to the regulator and wiring. There are many online resources with instructions specific to a 1999 Malibu. Be careful not to damage any clips when removing the panel.
2. Inspect the regulator: Check for broken cables, cracked plastic, or anything that seems out of place.
3. Inspect the window tracks and window itself: Look for debris, damage, or misalignment.
4. Inspect the wiring: Carefully check the wiring for any breaks, frays, or loose connections.
5. Test the motor directly (if possible): With the door panel removed, you might be able to directly power the motor to confirm it is still working correctly. (Caution: Be very careful when testing electrical components in a car. Disconnect the battery negative terminal if you're unsure.)
If you're not comfortable working on car repairs, it's best to take your Malibu to a mechanic for diagnosis and repair. The problem could be more complex than it initially seems.
