1. Identify the Source of the Leak:
* Timing: When does the leak occur? During rain? After washing the car? This narrows down potential areas (sunroof, window seals, etc.).
* Location: Precisely locate where the water is entering the cabin. Is it dripping from a specific spot on the headliner, carpet, or dashboard? Mark it with tape.
* Water Test (If possible): If it's raining, try to observe where the water is coming from. If not raining, carefully and slowly use a hose to simulate rainfall, focusing on suspect areas. Have someone inside the car to identify where the water is entering. Start with the sunroof, windows, and windshield, then move to other possible entry points.
* Suspect Areas:
* Sunroof: Check the sunroof drain tubes. These can clog and cause water to overflow into the car. Clean them out with compressed air or a flexible wire. Also inspect the sunroof seal for cracks or damage.
* Windows: Inspect the seals around all windows for cracks, gaps, or deterioration. Replace damaged seals.
* Windshield: Check the windshield seal for any gaps or damage. A leaking windshield is a serious issue and usually requires professional replacement.
* Door Seals: Examine the door seals for cracks or deterioration. Water can easily seep in through gaps. Replace damaged seals.
* Firewall: Leaks can sometimes occur around the firewall (the partition between the engine compartment and the cabin). This is a more difficult area to access and repair, often requiring professional help.
* AC Drain: The AC drain tube can clog and cause water to leak inside the car. Locate and clear the drain.
* Weather Stripping: Check all weather stripping around doors, windows, and the trunk. Replace worn or damaged parts.
2. Repair the Leak:
The repair will depend entirely on where the leak is coming from. Here are some general repair methods:
* Sealant: For minor leaks in seals, a high-quality automotive sealant might suffice. Apply it carefully and according to the manufacturer's instructions.
* Seal Replacement: Damaged seals (window, door, sunroof) will likely need to be replaced. This often requires removing the window or door panel, which can be a challenging DIY job.
* Drain Cleaning: Clogged sunroof drains or AC drains need to be cleared using compressed air or a small flexible wire.
* Professional Help: Leaks around the windshield or firewall are best left to professionals, as these areas require specialized knowledge and tools.
3. Drying the Interior:
After fixing the leak, you'll need to thoroughly dry the interior to prevent mold and mildew growth.
* Remove Wet Materials: Remove any wet carpets, mats, and other affected materials.
* Air Circulation: Open all doors and windows to allow for maximum airflow.
* Dehumidifier: Use a dehumidifier to speed up the drying process.
* Fans: Place fans to circulate air.
Important Considerations:
* Safety: Always disconnect the battery before working on any electrical components.
* Patience: Finding and fixing interior leaks can be time-consuming. Be patient and methodical in your approach.
* Tools: You may need basic tools like screwdrivers, pliers, and possibly a sealant gun.
* Parts: Replacement seals and other parts can be purchased at auto parts stores.
If you're not comfortable tackling this yourself, it's best to take your Cavalier to a qualified mechanic. Interior leaks can be tricky to diagnose and repair, and a professional can ensure the job is done correctly.
