A/C Service and the Cabin Air Filter

It is amazing how a little dirt can affect an air conditioning system.

If a cabin air filter is allowed to remain past its service interval (anywhere from 15,000 to 30,000 km) it can cause musty odours in the vehicle, and over time, the heater and air conditioner may become damaged by corrosion. A dirty or clogged cabin air filter can also cause contaminants to become so concentrated in the cabin that passengers actually breathe air that is worse than outside the car.

Naturally, it can also impede the flow of air possibly leading the technician to misdiagnose a lack of cooling as a stuck blend door or a failing blower motor.

Most cars have one cabin air filter, though some premium vehicles can have two or three. The filters are usually found either under the dashboard, behind the glove compartment, or in the engine compartment.

Filters housed under the dashboard are usually located between the blower and the rest of the heating, ventilation and air conditioning case. Of the three filter locations, this can be the most complicated to reach. Cabin air filters located behind the glove compartment are generally the easiest to replace. In some vehicles, the glove compartment will have to be removed in order to access the filter compartment. Other vehicles have glove compartments that can be flexed enough to reach this compartment. Once the box has been removed or flexed open, unlatch or unscrew the compartment door to access the cabin air filter. Pull the filter from the compartment, and then insert the new filter.

Cabin air filters under the hood are usually positioned near the air intake. Remove the air intake screen, as well as any weather stripping that may be protecting this area. The filter may be found in a plastic housing beneath these covers, or fastened into place.

It is advisable to clean the area (a vacuum is best) as dirt and debris can collect in the cabin air filter housing. Failing to do this may result in dirt and debris being drawn into the vent system, which will not please the customer.