* Sunroof Drain Tubes: Clogged sunroof drain tubes are a very frequent cause. These tubes are designed to carry water away from the sunroof, but if they become blocked with debris, water can overflow and enter the cabin. Check the drain tubes (usually located at the front corners of the sunroof) and ensure they're clear.
* A/C Condensation Drain: The A/C system produces condensation, which normally drains outside the car. However, a clogged or improperly routed drain can lead to water pooling inside the car, often on the passenger side. This is more likely to be a slow, steady drip rather than a sudden puddle.
* Windshield Seal: A leak around the windshield is another possibility. Water can seep in through a cracked or deteriorated seal, especially during heavy rain. Inspect the seal carefully for any cracks, gaps, or damage.
* Weatherstripping: Check all weatherstripping around doors and windows, especially on the passenger side. Deteriorated or damaged seals can allow water to enter.
* Blocked HVAC Drain (Heater Core): While less common, a blocked drain related to the heater core could potentially cause a leak. This is usually associated with a musty odor.
* Firewall Leaks: Water can sometimes find its way through holes or cracks in the firewall (the partition between the engine compartment and the passenger compartment). This is a more difficult problem to diagnose and repair.
How to Investigate:
1. Start with the easiest: Check the sunroof drains first. This is often the culprit and the easiest to fix.
2. Inspect the A/C drain: Look for evidence of water dripping from under the dashboard. Sometimes you can gently clear the drain with a small wire or compressed air.
3. Check weatherstripping: Look closely for any damage or gaps in the weatherstripping around the doors and windows.
4. Visual Inspection: During a rain storm, carefully observe the car from the outside to see where water might be entering.
5. Water Test: If you can't visually identify the leak, try using a garden hose (carefully!) to simulate rain and see where the water enters. Have someone inside the car to observe where the water is coming in.
If you can't find the leak yourself: Take your Impala to a trusted mechanic. They have the experience and tools to diagnose and repair the leak effectively. Don't ignore the problem, as continued water intrusion can lead to rust, mold, and electrical issues.
