1. Identify the Problem:
* Door won't open from the outside: This could be a problem with the exterior handle, the linkage connecting the handle to the latch, the latch mechanism itself, or the actuator (if it's power-locked).
* Door won't open from the inside: This points towards a problem within the interior handle mechanism or the latch itself.
* Door opens and closes but feels loose or flimsy: This suggests a worn latch or loose linkage.
* Intermittent problems: This often points to a wiring issue if it's a power-locked system, or a sticky mechanism.
2. Troubleshooting Steps:
* Check the Exterior Handle: Make sure the exterior door handle moves freely and connects properly to the linkage. Sometimes the linkage can become disconnected or broken. Inspect it carefully.
* Check the Interior Handle: Make sure the interior handle moves freely and is properly connected to the latch mechanism. Lubricate it if it feels stiff.
* Check the Door Latch Mechanism: This is the most likely culprit. Access it by removing the interior door panel (search YouTube for "Mercury Cougar [year] interior door panel removal"). Inspect the latch for broken parts, worn components, or binding.
* Check the Actuator (if power-locked): If your Cougar has power door locks, the actuator could be faulty. You'll need to test its operation and potentially replace it. This often requires electrical knowledge.
* Check the Rod Linkage: Examine the connecting rods between the exterior handle, interior handle, and the latch mechanism. Look for broken or bent rods, or areas where the rods might have come loose from their mounting points.
* Lubricate: Apply a small amount of white lithium grease to any moving parts of the latch mechanism to address stiffness. Avoid using WD-40 as it's a solvent and will eventually evaporate, leaving the mechanism drier than before.
3. Repair or Replacement:
* Minor Repairs: If you find broken or bent linkages, you may be able to repair them with replacement parts or by carefully bending them back into shape.
* Latch Replacement: If the latch mechanism itself is faulty, you'll likely need to replace it. You can find replacement door latches at auto parts stores (online or local) and often specify your Cougar's year and model for the correct fit.
* Actuator Replacement: Replacing a power door lock actuator usually requires some electrical knowledge and access to a replacement part.
4. Tools You Might Need:
* Screwdrivers (Phillips and flathead)
* Panel removal tools (to avoid scratching the door panel)
* Pliers
* Grease gun or tube of white lithium grease
* Replacement parts (latch, linkage, actuator, etc.)
Important Considerations:
* Year and Model: The exact repair procedure will vary slightly depending on the year and model of your Mercury Cougar. Make sure to specify this when searching for repair information online or at auto parts stores.
* Safety: Always disconnect the negative battery terminal before working with any electrical components. Be careful when removing the door panel to avoid damaging the wiring or other components.
* Professional Help: If you're not comfortable working on car repairs yourself, it's best to take your Cougar to a qualified mechanic.
By following these steps, you can systematically diagnose and fix the problem with your Mercury Cougar's driver's side door latch. Remember to search YouTube for videos specific to your Cougar's year and model for visual guidance. This will greatly aid in the process.
