Unpleasant smell from car AC? Most drivers make this mistake, experts say

Many drivers may be unaware of a simple mistake that leads to unpleasant smells and reduced airflow from their car's climate control system: a clogged cabin air filter. This essential component filters dust, debris, leaves, and pollen from the air entering the vehicle, directly impacting the efficiency of the heating, ventilation, and air conditioning (HVAC) system.

Experts suggest a simple habit to combat moisture buildup, the primary cause of musty odors. Turning off the air conditioning (A/C) button a minute or two before reaching your destination, while keeping the fan running, helps dry the interior of the system. This prevents the accumulation of moisture, which can lead to the growth of mold and microorganisms, often mistaken for a malfunctioning A/C unit.

However, this habit should not replace regular filter maintenance. Auto mechanic Eddy Soto explains that the cabin air filter "filters the air in the cabin, collecting pollen and dust particles," thus helping to maintain fresh air. A dirty filter leads to stale cabin air, weaker airflow, and can strain the A/C and heating systems, forcing them to work harder.

Signs that the cabin air filter needs replacement include noticeably weaker airflow from vents, persistent unpleasant or musty odors, and increased allergy symptoms while driving. Difficulty defogging windows or a louder-than-usual A/C system can also indicate a clogged filter. Experts recommend replacing the cabin air filter approximately every 12 to 18 months or every 12,000 to 30,000 miles, depending on driving conditions. Drivers in dusty areas or those with high pollen or pollution levels may need to replace it more frequently. The replacement process is generally straightforward and can often be done at home within about 15 minutes.

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filters the air in the cabin, collecting pollen and dust particles