why does my BMW 3 Series E90/E91 have condensation inside the windows?

Solution

1. Preparation

• Gather tools and materials needed for repair.
• Ensure the vehicle is parked on a flat surface and the engine is off.
• Disconnect the battery if working on electrical components.

2. Inspect and Replace Seals

• Inspect Seals:
  • Check the integrity of door, window, and windshield seals.
  • Look for cracks, tears, or areas where the seal is not making contact.
• Replace Damaged Seals:
  • Remove the old seals carefully using a trim removal tool.
  • Clean the surface where the new seal will adhere.
  • Apply adhesive if required (follow manufacturer's specifications).
  • Install new seals, ensuring they are seated properly.

3. Clean and Replace Cabin Air Filter

• Remove Cabin Air Filter:
  • Locate the cabin air filter housing, usually under the dashboard or behind the glove box.
  • Remove any panels or covers as needed.
  • Pull out the old cabin air filter.
• Install New Cabin Air Filter:
  • Insert the new filter in the correct orientation (check for airflow direction).
  • Reassemble any housing or panels removed.

4. Address Water Leak Sources

• Inspect Drainage:
  • Check drainage channels around the sunroof (if equipped) and ensure they are clear.
  • Clear any blockages in the drainage holes.
• Seal Windshield or Windows:
  • If leaks are detected around the windshield or windows, consider applying a sealant specifically designed for automotive use.
  • Allow the sealant to cure as per manufacturer's instructions.