1. Binding in the Regulator: This is the most common issue. The window regulator is the mechanism that uses the motor's power to raise and lower the glass. Over time, the plastic parts can crack, break, or become worn, causing binding. The cables can also fray, become dislodged, or seize up. This is especially likely given the age of the car.
2. Window Track Issues: Debris, dirt, or corrosion in the window tracks can prevent smooth movement. The window may be rubbing against the felt or metal guides.
3. Window Stuck/Jammed: Something might be obstructing the window's path – a piece of weatherstripping, a foreign object, or even a warped window itself.
4. Faulty Switch (Less Likely): While you say the motors work, a weak or intermittently failing window switch could still be drawing power without properly engaging the motor, creating a situation where it seems like the motor isn't moving the window.
How to Troubleshoot and Fix:
1. Check for Obstructions: First, visually inspect the window track and the area around the window. Remove any debris or obstructions you find. Try to gently move the window up and down manually to see if it's jammed.
2. Inspect the Regulator: This requires removing the door panel. There are many online tutorials specific to 1991 Lincoln Town Car door panel removal (search YouTube for "1991 Lincoln Town Car door panel removal"). Once the panel is off, carefully inspect the regulator mechanism. Look for:
* Broken plastic parts: This is common in older cars.
* Frayed or dislodged cables: These need to be reattached or replaced.
* Bent or broken metal components: These might need repair or replacement.
* Excessive wear and tear: This may indicate the regulator needs replacing.
3. Clean the Tracks: Thoroughly clean the window tracks using a brush and degreaser. Apply silicone-based lubricant to the tracks to reduce friction.
4. Test the Motor (again): With the door panel off and access to the regulator, directly test the motor. If you have a multimeter, check its voltage and current draw while attempting to operate the window. If the motor isn't working now, the issue is the motor itself and will need replacing.
5. Consider the Switch (if other windows work): If all other windows have the same problem, the regulator is likely the culprit. If only one window is affected, you may want to test the switch.
Repair or Replacement:
* Minor Issues: Cleaning the tracks and addressing minor binding might be enough to restore functionality.
* Regulator Repair: If the regulator's damage is limited, you might be able to repair it (e.g., replacing a broken plastic piece or reattaching a cable). This requires some mechanical aptitude.
* Regulator Replacement: A complete regulator replacement is often the most practical solution. You can purchase replacement regulators online (e.g., eBay, Amazon) or from auto parts stores. This requires some mechanical skill and the ability to follow repair instructions.
Important Note: Working on car door mechanisms can be tricky. If you're not comfortable with car repairs, it's best to take your Lincoln to a qualified mechanic. Improper repair could lead to further damage or injury.
