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Cabin Air Filters: Are You Recommending a Filter Replacement?
By: Larry Hammer | Friday, December 20th, 2019 at 3:07 pm in On The Line

Cabin Air Filters: Are You Recommending a Filter Replacement?

Two lungs filled to capacity with air contaminated with rotting bugs, molded leaves, dust, pollens, mold spores, mildew and other pollutants doesn’t sound healthy. With a contaminated cabin air filter that is exactly what the customer is breathing.


Often, when approaching a customer with a cabin air filter replacement recommendation the response is, “What’s a cabin air filter?” This filter is out-of-sight and out-of-mind, but it plays an important role in keeping the passenger compartment free of harmful contaminants. Studies have proven that the air in the passenger compartment may contain a level of contamination six times greater than that of a pedestrian. This is especially a problem in areas of high traffic, as the roadside air contains dust, pollen, diesel particulates, and smog. The filter should be replaced annually or every 12-15K miles. The replacement interval may be more frequent in dusty environments or areas heavily contaminated with bugs and other elements of contamination. For show-and-tell, keep a contaminated air filter accessible when making a cabin air filter replacement recommendation to the customer, as seeing can be more convincing.

Two types of cabin air filters are commonly used in automotive applications:

  1. Particulate filters…designed to remove dust, bacteria, mold spores, pollens, and other pollutants.
  2. Combination filters…which are charcoal/carbon impregnated filters designed to remove the previously mentioned pollutants, in addition to harmful gases and odors.

People that suffer from asthma, allergies, or hay fever can benefit the most from the removal of airborne allergens, mold spores, pollen, and dust. These contaminants can trigger dangerous breathing conditions that would not influence a person with a healthy respiratory system. When these symptoms occur, they can come quickly and be life-threatening. Replacing the cabin air filter on a regular basis can help prevent these symptoms.


Customer complaints of reduced airflow from the vents may be the result of a restricted cabin air filter. When this condition is present, place the A/C controls in the Max (recycling inside air) position. If the airflow is increased in this position, a restricted cabin air filter should be your first check. Some vehicle manufacturers place the cabin air filter between the blower motor and the evaporator. In those vehicles, a restricted cabin air filter will prevent good airflow in any mode of operation.

The cabin air filter prevents the evaporator and heater core from becoming clogged with debris such as dirt, leaves, and bugs, which can result in restricted airflow, affecting the system’s efficiency. In addition, the filter prevents debris from collecting on the evaporator core where it can absorb moisture, promoting fungal growth and foul odors. A clean filter prevents fogging of the windows, which can restrict visibility. Reducing the formation of these deposits can prevent corrosion and premature failure of the AC components.

The evaporator is a breeding ground for fungus and microbial growth. Some vehicle manufacturers offer chemicals and treatments to remove these contaminants. Ask your Mighty rep about A/C refresher kit CL120. It destroys odors that may be caused by mold, mildew, and fungus. Some treatments are performed through a port entry in the evaporator housing, while some applications may require the removal of the evaporator for cleaning and treatment. Removal of the evaporator can be a major exercise and a substantial cost to the vehicle owner.

Summary: Most vehicle owners are aware of the required service for the oil, air, fuel and transmission filters, but have no knowledge of the cabin air filter and the need to keep the ventilation system clean. Making the installation of the filter is a quick and simple procedure, requiring an average of five to ten minutes to complete, except for a few vehicles. The filter comes packaged with an installation guide chart and an estimated time to replace it. Make the cabin air filter a part of your service recommendation.

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