Dealing with Mold in Your Vehicle's AC System

Its called “sick car syndrome” and it smells like your teen’s neglected gym bag.

A vehicle’s A/C system works by condensing heat and moisture in the outside air, pushing cooler air into the car. Since the evaporator coils are colder than surrounding air, moisture naturally collects, creating pools of water which should exit via the drain line. When moisture can’t find its way out, it stays inside the unit. This may occur if the drain line is blocked or damaged, or the system is used too often without time to dry out.

Mold needs moisture, darkness, and food to thrive. Your vehicle’s AC system naturally provides the first two components, while pollen in the air, dead insects and leaves provide the food. Mold in a vehicle’s A/C system can cause sneezing, coughing, headaches, weakness, drowsiness or fatigue and other of flu-like symptoms. In one study, 8 varieties of mold were found in 22 out of 25 tested vehicles.

While severe mold issues can only be treated by a certified mechanic, mild issues might be successfully tackled using these DIY tips.

Check the drain line: When the A/C is in use, you should see water draining from the vehicle. If not, check the drain line for clogs.

Avoid recirc: As often as possible, keep recirc off, which prevents outside air from entering the car.

Dry out before turn-off: 2-5 minutes before turning off the vehicle, turn the A/C off, leaving the fan on high. This allows the unit to dry out.

Replace air filters: Dirty air filters reduce airflow, keeping moisture in the A/C system and stressing A/C components. At a minimum, follow your vehicle manufacturer’s recommended replacement interval for engine air filters and cabin air filters. Replace filters more often if you live in a dusty environment.