Mold spores can spread throughout the entire vehicle.

How to Clean Mold in a Car's Air Conditioning System

Last updated September 08, 2012

How to Clean Mold in a Car's Air Conditioning System. A car's air conditioning system is susceptible to moisture invasion via condensation from the AC evaporator, or a leak somewhere in the fresh air intake system. Stagnant water can accumulate in the lowest parts of the system, creating mold. Mold is a fungus, and it can irritate the nasal passages.You can rid your AC vents of mold by using a few specialized tools and products.

Things Needed

  • Vehicle owner's manual
  • Phillips screwdrivers (if applicable)
  • Cabin air filter
  • Spray bottle
  • Full-strength white vinegar
  • Particle mask
  • Butter knife (if applicable)
  • Long-handled brush
  • Terrycloth towels
  • Air freshener appliance
  • Cabin Air Filter

    Step 1

    Read your owner's manual for the location of your cabin air filter, if applicable. You might have two located in different areas. Generally the cabin air filter is located just behind the glove box or inside the engine compartment next to the passenger-side firewall. The air filter box will have pull tabs, spring release locks or screws holding the cover. Manually remove the cover by its locking device or use a Phillips screwdriver to remove the screws. Examine the filter. If it is soaked with water or damp with mold, replace it.

    Step 2

    Fill a spray bottle with white vinegar and spray the inside of the cabin air box and vent. Project the spray as far into the vent as possible, spraying a dozen squirts. Clean the air box with towels and place a new air cabin filter in the box. Re-snap the box lid or insert the screws with the screwdriver. Spray the fresh air intake vents located under the grille that sit at the base of the front windshield. Apply multiple squirts for a heavy dose.

    Step 3

    Don a particle mask and open up all the doors of the vehicle. Locate the AC vents on the dashboard and open them up. If they have a removable plastic vent screen, snap it out by hand or wedge a butter knife into the seam and pop it out. Spray copious amounts of white vinegar into all the vents, soaking the vents' interior. Take a long-handled brush, such as a fish tank wire-handle brush, and swab the interior channels of the vents as far as you can reach inside. Re-spray the vents again and replace the vent screens if you have removed them. Wipe up any excess vinegar with a towel. Let the vinegar soak for two hours or more, to kill the active spores. You can let the solution stay overnight.

    Step 4

    Start the vehicle and turn on the flan blower to maximum cool. Spray more white vinegar into the outside fresh air intake grille. Let the blower run for 3 to 5 minutes and wipe the excess vinegar from the vents. Turn on the AC maximum cool setting and engage the recirculating mode. Close the doors and roll up the windows. Let the AC run for 5 to 7 minutes. Place an air freshener appliance in the vehicle.


  • If the presence of mold or its smell persists after your treatment, it means that the AC drain tube could be clogged and the evaporator pan is moist with mold. In this case you will need to jack up the vehicle and refer to your owner's manual for the location of the small rubber drain tube. To clean an obstruction in the drain tube, use a small can of compressed air to blow into the tube and free it of debris. The tube should then dispel condensation normally, disallowing water to accumulate in the evaporator pan. Seek professional mechanical help if you are in doubt about performing the procedure.


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