Improve your customers’ well-being through cabin air filter education

It is amazing to think that nearly every vehicle in the world now utilizes cabin air filtration, and the technology has grown, leaps, and bounds, since it’s inception. Freudenberg is still a market leader as an OEM supplier in today's market. In 1989, Freudenberg's first year of production yielded a mere 35,000 filters (FIG 1). In only four years, production increased more than 100 times over, at 3.6 million filters manufactured in 1993 (and numbers continued to trend higher, as the years went by). Like many of the other manufacturers to be mentioned. Freudenberg invested time and energy, working alongside the automotive industry, air conditioning manufacturers, research institutes, regulatory bodies, and public institutes, to provide the best filtration technology has to offer. As a Freudenberg filtration application engineer, Dr. Hans Reinhardt stated it, “It [Freudenberg’s] was our mission to improve human health and well-being that inspired the change in focus from the engine to the people inside the vehicle."

Figure 2

It began with the micronAir filter when more than 30 years ago, it became the first cabin air filter for serial production. Beginning with the Mercedes-Benz SL Roadster in 1989. In 1991, the Opel Astra was the first mass-market vehicle with the micronAir filter (FIG 2). This Initiated not only a new product category but also an entirely new industrial branch.  Designs initially used an innovative pleated filter medium, providing unprecedented protection against pollen and dust particles that could also be tailored to create different levels of efficiency. Premium manufacturers can specify the highest possible filtration performance, while manufacturers in the mass markets can make sensible compromises between efficiency and price. This left a few options for both shops and customers to choose from.

As time went by, so did the customers' demand for cleaner, healthier in-cabin air quality. In 1995, the first combination of filters (Combifilters) rolled off the production line. These filters boasted a layer of activated carbon and the filter medium provided added protection against harmful gases and unpleasant odors. The filters were then not only capable of small particulate filtration (like sand, dust, diesel soot) but also capable of filtering harmful gasses like Hydrocarbon (gasoline vapors) Sulphur-dioxide, Nitrogen-dioxide as well. This advancement in technology greatly improved the air quality within the vehicles’ cabins. This is the baseline for what we know as cabin filtration.

Why make such a “stink” over the air quality of the cabin?

Considering Americans drive (on average) more than 13,000 miles per year with an average of 100 miles of daily driving, we place ourselves within the cabin of our vehicles quite frequently and for long durations of time. That's a combined total of 6.9 billion hours in the cabin, each year! This is the reason why over 90 percent of all vehicles sold within the US utilize cabin filtration technology. Studies show that the air quality within the vehicle tends to be upwards of six times as polluted than that of the air outside the vehicle. Traffic congestion equates to a large contributor to deteriorated air quality. As we sit still, the harmful gasses that leave the exhaust systems of nearby vehicles makes its way into the cabin of the vehicle we (and our passengers) are seated in. Dust from worn tires and soot from diesel emissions finds its way in, too. And for those that suffer from allergies and other lung health issues, spores/mold/mildew/fungi will also tend to infiltrate, threatening our health and well-being. These concerns were the driving factors in the development of the cabin air filtration technologies that exist today.

For example, manufacturers like Airsept, PremiumGuard, Valeo, Mahle, Fram, and TYCGenera (just to name a few) are companies that have invested a lot of time and energy into the research and development of a quality cabin air filter product, to combat the undesirables mentioned above.

These filters are offered at different levels of efficiency (and are reflected in the price) to provide the customer with a customized level of protection, at an affordable price range. PremiumGuard’s Particle cabin filter boasts 99 percent entrapment of airborne contaminants that enter the cabin (FIG 3). These include dust mites, sand, pollen, diesel soot and tire dust. The cabin filters work to remove these contaminants from the airstream without affecting the efficiency of the airflow within the HVAC system.

They also offer a filter product line with an advanced level of protection. Their activated charcoal cabin filters have charcoal embedded in the filter media. These filters not only protect against the undesirable particulate contaminants mentioned above. They also can absorb harmful gasses like Nitrogen-dioxide (NO2, which is absorbed through the lungs and can lead to heart failure and death, in heavier concentrations), Hydrocarbons (HC, found in gasoline and other fuels, another poisonous gas), as well as Ozone. The filters even capture the particulates that, when combined with moisture from the evaporator's condensate, promote the growth of mold spores and fungus (a major contributor to the awful odors that tend to occur in an HVAC system).

Figure 4

There are three layers of filtration that take place within the PremiumGuard filters. The first is designed to eliminate the particulates larger than 10um (10 microns= .000394 inches in diameter). The second layer is designed to trap the mold spores and harmful gasses including Carbon-monoxide and Sulphur-dioxide (CO+ SO2= both toxic bi-products of combustion where CO is odorless but SO2 can tend to exhibit the smell of "rotten-eggs"). The third layer has an amazing antibacterial property in which we will discuss below (FIG 4).

Valeo is the only supplier that not only designs its cabin filter but also, the AC systems they reside in. Their particulate cabin filters offer filtration of particles as small as 0.1um ( that is only one-tenth of one millimeter in diameter. According to COVID-19 expert, Dr. Gregory Poland, the virus measures a diameter of 0.12um). They too, offer combifilters but, with up to four layers of filtration. The first layer is for rigidity and support. The Absorbent layer is of a non-woven material with active charcoal particles embedded within. And two additional filtering layers of porous pleated filter paper. Together, these four layers are capable of particulate filtration and filtration of gaseous contaminants (like the ones mentioned above). These include NOx, butane, toluene (Paint-thinner), and butadiene, using the activated carbon layer (FIG 5).

Mahle boasts maximum filtration capabilities with a minimum pressure drop across the filter (will not impede airflow). This is due to their extra-large surface area of filtration. Their “CareMetix” filter has a filter media capable of only 2.5-micron filtration but, retains ultra-high efficiency for airflow which means longer service intervals for your customer (FIG 6).

Figure 6 Figure 7

Fram produces a filter they call FreshBreeze. Working hand in hand with Arm+Hammer baking soda, the filter traps and removes over 98 percemt of road dust and pollen (5-100 microns) and uses the embedded baking soda as a deodorant, to deliver odor-free air to the cabin (FIG 7).

TYCGenera tests its filters to ensure that they meet and/or exceed the OEs for pressure-drops in simulated dust-environments. They also utilize additional brackets, seals, and gaskets for secure installation but, equally as important, optimum capture-rate. In many cases, better filtration than that of the OE filter, without the price.

Regardless of the brand and level of air quality and filtration you desire, an important characteristic of the combifilter is its ability to neutralize allergens from pollen. It contains a natural surface treatment on the filter media called Polyphenol.  Polyphenol is a chemical that can found in items like a natural grape seed. It is known for its anti-allergenic properties and effectively eliminates pollen allergens like cedar and even dust mites (which measure as small as .3 microns). The Polyphenol works by chemically deactivation the allergen molecule, reducing the effect by more than 88 percent, by itself. This offers a 150 percent improvement over conventional cabin filter entrapment of allergens. Furthermore, these conbifilters are typically electrostatically charged providing better particulate and allergen entrapment, once the Polyphenol coating has deactivated the contaminants.

Studies show that while running an HVAC system (on medium-low fan speed, in a recirculated fashion), 90 percent of the particulates airborne within the cabin were eliminated in under 5 minutes. 99.5 percent elimination of particulates was achieved in just 15 minutes! How's that for "filtration"?

Filter replacement: An inexpensive alternative to a very expensive repair

It is clear to see the benefit of improved air quality, with the use of cabin air filters. Even more so for our customers that suffer from allergies, asthma, and other health and lung disorders. But, let's talk about some of the other consequences of ignoring the simple and often neglected replacement of the vehicle's cabin filter.

The obnoxious odor is one of the first signs of the need for filter replacement, but it is not always that simple. I've personally seen vehicles enter the shop with the complaint of "foul odor" only to lead to expensive and time-consuming replacement of not only floor mats but also headliners, carpets, and ozone-treatments. The root-cause was true, a neglected and contaminated cabin air filter. A simple replacement (at the factory recommended service interval) and a trip down the highway with the windows open, is all the vehicle needed.

How about the rest of the HVAC and heating system? How quick are most technicians (who are face-to-face with an AC-performance complaint) to inspect the cabin air filter? After all, it's the convection that takes place between the air and the heat exchangers (heater core/evaporator) that make us comfortable within the cabin. If that air can't flow, the efficiency of both the heating system and the AC system suffers dramatically. How many unnecessary and expensive HVAC-misdiagnoses are there likely to be?

Considering that the cabin air filter is the last line of defense for the components within the dashboard, how likely is it that the longevity of the HVAC ventilation actuators and doors and the heat exchangers will suffer from premature failure? Logic will dictate that added dirt and other particulates will inhibit the smooth operation of the door and actuators. Most of the electronically controlled systems of today’s vehicles are capable of self-diagnostics. Many times as technicians, we are faced with circuit codes due to mechanical deficiencies within the dashboard (FIG 8). Often, misdiagnosis leads to costly actuator replacement when, in fact, debris inhibited door movement and was the root cause of the failure. Sometimes the actuators themselves are the weakest link, due to the plastic-gears within them, driving the mechanical doors, throughout the life of the vehicle (FIG 9). Needless to say, these repairs tend to be very expensive on some models. This example is from my own 2006 Chevy Silverado. The labor to replace the recirculation door actuator is six hours. Imagine the look on the customer’s face when the root cause is due to filter that should’ve been replaced previously. Perhaps the shop replacing the actuator was the same shop that failed to inform the customer…ouch!

Figure 9

That isn't the extent of the potential failures. Consider the growth of mold, bacteria, and fungus that occurs with an abundance of organic material (like leaves and dust) collects on the surface of an evaporator (causing it to become compromised) or, even the copper from a worn blower motor armature (this can have a galvanic reaction with the aluminum and cause the evaporator to leak). Never mind the smell!

Just a few tips to keep in mind when performing routine maintenance and courteous multi-point inspections of the vehicles we face daily. Be mindful of the factory maintenance schedule and realize that not every carline has a filter and, that locations vary. Remember that there may be multiple options for a customer. Not every customer suffers from breathing issues so, a basic filter may suffice in those situations. It is better to have a filter with less capability in place than none, at all. Remember that with a little thought and understanding of a filter's location some diagnostic strategies can be derived. For instance:

If a severely-restricted cabin filter is located near the air inlet, the AC and Heater performance/airflow will suffer, so long as the system is placed in "fresh-air" mode. If it is selected for "recirculation" the symptom tends to vanish. This would not be the case if the filter was located between the blower motor and the evaporator.

As technology progresses…

As you can see, technology has come a long way, in the hunt for the healthiest cabin-air we can provide for our customers. An adequately maintained HVAC system includes proper air flow within it. That means a regularly replaced cabin air filter. Although different filters require different intervals, its common to see intervals call for replacement annually or every 15,000 miles. 

You will be sure to see some auxiliary systems for air quality, working in tandem with cabin air filters, well into the future. These include:

Cluster ionizers — Generates electrically charged air molecules that attract the undesirables and then adhere to a collection plate

Plasma-cutter Ionizers — Functions by chemically disassociating hydrogen molecules from a microbe, to make it inactive. The microbes are then collected within the cabin filter, like particulates.

Fragrancing — Perfumes are offered by manufacturers like Mercedes-Benz, to improve the scent within the cabin. They typically last a few months and are replaceable at the dealer

Aromatherapy — Some manufacturers (Nissan) offer the ability to add aroma and humidity for better mental state and stimulation for the driver. Systems like these can alternate between a couple of different scents and can erratically alter volume and direction of the air leaving the ductwork, to simulate a breeze in nature

Air-quality sensors —   Air-quality sensors can be found in today's vehicles. Manufacturers like Ford, GM, BMW, Volvo, and Toyota all use them in newer vehicles. The components give the vehicle the ability to change between fresh-air and recirculation, without driver input. It allows fresh-air when there is an abundance of CO2 (an abundance of CO2 reduces driver's awareness and promotes drowsiness) and will command recirculated air when passing through tunnels and such that the abundance of harmful gasses is present outside of the vehicle.

Like any other technology we are faced with, knowledge is not only power but, it’s also profitable.