Clear the Way

• Air conditioner condensation dripping onto the interior passenger floor is a strong indication of evaporator drain blockage. The drain is located under the hood, at the firewall or the evaporator housing. Using a small mirror and flashlight may avert the need to get under the car to inspect the drain. Any visible debris should be removed by hand, if possible. Any probes you insert should be plastic, such as coffee stir sticks, to avoid damaging internal components.
  
  

Keep Your Cool

• Remove any underhood debris while making other routine checks.Stockbyte/Stockbyte/Getty Images
  
  Inspect the area just below the windshield for debris. The fresh air intake for the ventilation system is usually the point where debris enters the system. Remove any leaves or other debris you find, and maintain the area around the intake through occasional inspections. Clean the intake area whenever the hood is opened to check engine oil levels, or more often if you regularly park the vehicle under trees. The ventilation system blower motor may draw in any errant debris.
  
  

After Affects

• Once proper drainage is restored and confirmed, the interior must be thoroughly dried out to avoid mildew formation and odors. Use clean rags or paper towels to sop up the bulk of the moisture. A powerful vacuum cleaner that is equipped to handle wet pickups can pull most of the remaining dampness out of carpet or padding. Leave the windows down while the car is parked in a dry location for several hours, or until you can't feel any more moisture in the floorboards or carpet.
  
  

Odor Removal

• Eradicate musty smells left in the carpet with any available carpet and upholstery cleaner. Follow the product instructions for use, and allow the treated surfaces to dry thoroughly. Some products exist to deodorize the ventilation system by introducing the product into the fresh air intake. You can get the same effect by driving the vehicle in the rain with the ventilation set for fresh air. Light spray from a garden hose could substitute for rain.