There are many reasons why moisture gets on the inside of a vehicle. Most often the seal between a door panel and frame has deteriorated or a window is not rolled all the way up. Alternatively, an improperly installed windshield or door window can also cause moisture in a vehicle. Some instances can be fixed at home, while others require professional assistance.
Clean the vehicle. Some leaks maybe caused by an excess buildup of dirt and grime on the inside panels of the car. Give the vehicle a thorough cleaning and detailing. This should include the door track, door latch and weatherstripping areas on all vehicle openings.
Determine where moisture is leaking in. While it may seem obvious by the spots in a vehicle, it is still beneficial to double check. There may be more than one point of entry for moisture. Moisture is most often experienced inside of a vehicle after a heavy rain or several inches of melting snow. To determine this, you will want to water down the vehicle with a hose. Have one person on the inside to indicate where the leak is coming from.
Cut weatherstripping in the section where leak is if this is the source of the leak. Weatherstripping is designed to keep moisture outside and warm or cool air inside of a vehicle. Over time this can deteriorate from road grime, dirt and some abrasive chemicals that are used during car cleaning. Using the X-Acto knife, cut a slit downward--to the car frame--at two ends of the strip. This is rather flexible, therefore it should be easy to pull the weatherstripping off of the frame of the vehicle.
Scrape adhesive residue from car frame. Using a plastic scrape, slowly remove the remaining adhesive from the car frame. Once this has been removed, use soap and water to thoroughly clean the area of any residue, dirt or debris.
Cut and apply new weatherstripping. Measure the space and cut a new piece of weather stripping to ¼ inch longer than the measured length. Apply adhesive to the vehicle frame and attach new weatherstripping. Tuck the extra edge into the old weatherstripping. This alleviates any gaps in protection.
Apply automotive protectant to the weatherstripping and vehicle frame. Protectant creates a coat that keeps weatherstripping flexible so that it will not crack or break.
