Car Insurance

As many maintenance services are eliminated completely or have their intervals extended, a new one-the cabin air filter-has emerged.

When first introduced, cabin air filters were listed as 2-year/30,000-mile replacement items. The bottom line, however, is that the typical cabin filter lasts a year or even less, depending on where the vehicle is operated. Airborne dust, such as in desert areas, can shorten a filter’s life, as can airborne particles from industrial operations.

Unlike such items as engine oil and air filters, which almost always are in the straightforward category, replacing cabin air filters can be anything from a piece of cake to a time-consuming struggle, Either way, filter replacement can be a service worth pursuing. Depending on the vehicle mix in your shop, you may be called upon to:

* Replace a plugged filter with an equivalent unit.

* Install an upgraded filter. This can be one with added-value features that many customers will be willing to pay for.

* Install a filter kit where there was none as original equipment, or perhaps a filtering screen if its not possible to retrofit a filter. This can be an appealing service on those cars and light trucks that don’t have filters, but have encountered evaporator odor.

There are two basic types of cabin air filters-the particle-trapping type and the type that adds a charcoal layer for odor absorption. Within those two types, there are further variations.

Some particulate filters have two layers-one that traps larger particles and a second layer that’s electrostatically charged , to attract and hold smaller particles.

The first known OE cabin air filter was used on a Rambler in the 1970s, but the first ones to become a significant factor were on European luxury cars, particularly BMW and Mercedes in the late ’80s. The OE supplier was Freudenberg NOK, a German manufacturer, winch became a major player in the U.S. aftermarket with its Micronair brand. It has sinc-e attracted a lot of competition here, with DENSO, ACDelco, Bosch, DuPont, Fram, Purolator and WIX, among others.

The 1995 Ford Contour and Mercury Mystique compacts were the first domestic nameplates equipped with cabin air filters, perhaps because they were based on a European Ford (Mondeo) platform. They have a simple particulate filter that traps cigarette smoke and pollen particles, plus airborne dust.

The easiest installation of a cabin air filter for a vehicle maker is at the fresh air intake, accessible under the hood, and that’s what the Contour and Mystique have. The air intake location still is a popular one, although some shielding is necessary to protect the filter from snow or rain damage. Or you may get to it through the glovebox opening. If this type of filter is plugged, the outside airflow drops dramatically, a problem that gets noticed both in Heat mode and in normal a/c use. In Retire, when outside air isn’t used, airflow is almost normal, so if airflow is weak in all HVAC modes except Retire, that’s a tip-off that the cabin air filter is plugged.

Some cars have the filter in the HVAC case between the blower motor and evaporator core, so a plugged filter will restrict airflow in any mode. This location, however, has a couple of real advantages: For one thing, it clears the cabin air if a passenger is smoking. For another, it’s a barrier between the blower motor and the evaporator core. So it prevents copper debris from motor operation from getting to the cores aluminum face, where it can produce a galvanic effect, resulting in surface and eventual pinhole corrosion. The advantages notwithstanding, this is a more difficult location for a vehicle maker to employ for a technician to service.

The most important thing to know when you start selling cabin air filter replacement is which vehicles have it. That may be the toughest part of the deal, because not every model of a nameplate has it. It may be on only a top-of-the-line model, or it may not have been used before or after some model year. Even shop manuals don’t always list the cabin filter, particularly if the replacement procedure is a relatively simple one.

If you carry a major cabin filter line, you can check the catalog listings. But even the best of them may not go beyond 80% coverage, which means you might be ordering some replacements from the car dealer. You can make a simple inspection of the air intake under the hood, or look through the gap behind the glovebox. If the filter is in neither location, is not a familiar item to the dealer parts department, is not illustrated in the owner’s manual or on the maintenance schedule and/or isn’t listed in your suppliers catalog, it still might be elsewhere.