Here's what's likely happening:
* Worn or broken linkage: The arm that connects the wiper motor to the wiper blades is likely worn, broken, or disconnected on the driver's side. Over time, these plastic components can become brittle and crack, or the pivot points can wear out. This is the most common cause.
* Binding or seized linkage: Dirt, debris, or corrosion could be causing the driver's side linkage to bind or seize, preventing smooth movement.
* Incorrectly adjusted linkage: While less likely, the linkage on the driver's side might be improperly adjusted, preventing it from making full contact with the windshield.
* Broken wiper arm: Although less likely if the arm *moves* even a little, it's possible the arm itself is cracked or damaged.
Troubleshooting Steps:
1. Visual inspection: Carefully examine the linkage mechanism on both the driver's and passenger sides. Look for cracks, breaks, rust, or any signs of binding. Pay close attention to the connection points between the motor, the transmission arm (if there's a separate one), and the wiper arms themselves.
2. Check for debris: Clean any dirt or debris from around the linkage.
3. Manual test (with caution): With the ignition OFF, try manually moving the driver's side wiper arm. If it feels stiff or binds, you've likely found the source of the problem. Be gentle to avoid further damage.
4. Check the wiper motor itself: While less likely due to the passenger-side functionality, if the other steps reveal nothing, the motor itself could be starting to fail (though a completely failing motor would likely affect both sides).
In short: The problem is almost certainly mechanical, localized to the driver's side wiper linkage. A visual inspection is the first and most important step towards diagnosis. If you're not comfortable working on cars yourself, it's best to take your Civic to a mechanic for repair. Replacing linkage parts is usually a relatively inexpensive repair.
