FIGHTING A/C ODOR
Air conditioner odor complaints seem to keep coming back no matter what
treatment your customers try, right? The reason is that most odor treatments
are short-term, while the source of A/C odor is a combination of factors,
including airborne microorganisms, that naturally repeat over time. Many
products that are offered to control odor, such as disinfectants, may have a
relatively effective initial application. Unfortunately, even the strongest
disinfectant leaves no long-term, residual protection against the inevitable
repeat odor infestation.
CAUSES OF A/C ODOR
Air conditioning odors typically result from uncontrolled growth of bacteria
and other microorganisms in the evaporator. Research by independent
laboratories has found fungi such as Aspergillus, Cladesporium, Penicillium
and others growing on cooling coils and other A/C system areas.
How do these microorganisms get there? They are naturally present in outdoor
air, and are drawn into the evaporator during air conditioner operation.
Moisture also contributes to A/C odor formation. Most of the moisture that
condenses on cold surfaces inside the system drains harmlessly over time.
However, some moisture continues to cling to coil surfaces after the A/C
shuts down. Microbial contaminants in the air combine with this lingering
moisture in the evaporator. The warm, dark and moist conditions in the
evaporator provide an ideal breeding ground for bacteria, mold and mildew to
grow and generate musty odors.
WAYS TO REDUCE A/C ODOR
Some odor treatments are merely feeble attempts to cover up odor. Almost all
odor treatment products fail to provide a long-term residual effect that can
reduce the recurrence of odor. Here is a brief description of the
performance capabilities of various odor treatments by product type.
• Perfumes/Fragrances: Are designed to cover up odor with another, more
acceptable scent. Can be time-release agents. Cover-up perfumes and
fragrances cannot eliminate odor-causing microorganisms.
• Disinfectants: Destroy odor-causing microorganisms on contact. The typical
liquid disinfectant quickly evaporates or washes out of the system along
with the condensation that forms during A/C use. The next time airborne
bacteria enters the system, odor can begin again. For this reason,
disinfectants can require frequent repeat application to control odor.
• Smoke/Mist Application: Smoke and mist products combine a liquid
disinfectant with a fine spray application technology. The spray is directed
toward air intake vents inside the passenger compartment, so it reaches down
into the air conditioning evaporator, where odor-causing microorganisms
colonize and grow. Ease of application is a plus, but again, the
disinfectant quickly drains from the system, leaving no long-term protection
against odor recurrence.
• Air Filters: Catch and absorb particulates and some gases as they pass
through ducts to the passenger compartment. Many filters use activated
charcoal. Filters become saturated or their active ingredient loses
effectiveness over time, and must be replaced. Some filters cannot catch
gaseous odor molecules, which can be small. Filters do not eliminate the
source of odor-causing microorganisms.
• Baking Soda/Absorbents: Help absorb moisture, which is needed by
microorganisms in order to grow. Lack of moisture reduces the ability of
microorganisms to multiply and cause odor. Absorbents become saturated
quickly and allow odor to return, thus requiring repeat application.
• Chemical Reactants: Reduce odor by combining with molecules of the
odor-causing microorganism. The new, combined molecules must then be removed
(wiped up with a dry towel, washed away in a liquid, etc.) to complete the
odor treatment. Like liquid disinfectants, chemical reactants provide only a
short-term treatment, and can allow odors to return quickly.
• Antimicrobial agents: Have a wide range of successful microbial control
applications, from inhibiting fungal growth on boat hulls to preventing mold
and mildew growth in carpet and wall coverings. One unique antimicrobial
product used on mobile air conditioner odor combines its active ingredient
with an acrylic resin that is sprayed into the evaporator. The acrylic resin
dries onto the evaporator coils, forming a coating that sheds moisture
better than uncoated coil surfaces. The antimicrobial agent remains embedded
in the coating, where it kills or inhibits the growth of any microorganisms
that attempt to settle on the coated surface. Together, the antimicrobial
and acrylic resin coating last in the A/C system for up to three years,
protecting against moisture buildup and the growth of odor-causing
microorganisms.
DOWNSIZED EVAPORATORS TRAP MORE MOISTURE
As vehicles were downsized (while also increasing their glass content), A/C
system manufacturers reduced evaporator size while simultaneously increasing
fin count. These densely packed evaporators trap and hold more moisture.
To see this for yourself, dip your hand into a glass of water. As you remove
your hand from the water, quickly spread your fingers apart. No water will
bridge the gap between your fingers. Dip and remove your fingers again, this
time spreading them slowly to only a fraction of an inch apart. Water will
bridge the smaller gap between your fingers, and remain far longer than if
you open your fingers wide.
Information provided courtesy of AirSept, Inc
