Last updateTue, 17 Oct 2017 5pm

On The Road

Make sure to change that air filter

Photo By: courtesy of Donna McCord
Photo Courtesy Of Donna Mccord

A dirty air filter can reduce the efficiency of a car’s heating and air-conditioning systems.

Q: Now that the days are getting warmer, I want to use my air conditioner. But when I first turned it on last week, it didn’t seem to do a good job cooling my car down. Also, every time I turn on either the heater or the air conditioner, there is a foul smell. I went to a nearby auto repair shop and was told that nothing was wrong with the air conditioner – I just need a new cabin air filter. I am skeptical about that and wonder what a cabin air filter is and how that could fix my problems.

A: Despite the fact that most vehicles today have filters that clean the air entering the vehicle passenger compartment, the cabin air filter is one of the most overlooked service items.

It is important to understand that failure to change this filter periodically will adversely affect the health and safety of the vehicle occupants, reduce the efficiency of the vehicle’s heating and air-conditioning systems, and even hasten the demise of certain vehicle parts.

This filter is located in the air intake for the passenger compartment and filters dust, pollen, dirt and other allergens from the incoming air. At the same time, it prevents leaves, bugs and corrosive debris from filtering into the heating, ventilation and air-conditioning systems, which could affect performance. The buildup of leaves and debris is usually the cause of the foul smell you are experiencing.

Different types of cabin filters fit most vehicles. The standard filter traps most particles larger than 3 microns in size. A better filter is electrostatically charged so that it can trap particles as small as 0.3 microns. The best of the cabin air filters contain activated charcoal, which helps remove odors, fumes and gases.

The easiest way to determine whether a vehicle has a cabin air filter is to check the owners manual or ask a service technician. These filters are usually located behind the glove box or under the hood near the base of the windshield, and are reasonably easy to change.

The result of not changing the filter is a gradual buildup of contaminants that will prevent it from properly filtering the incoming air, allowing foul smells, bacteria and allergens to enter the passenger compartment.

Additionally, when less air is able to pass through a clogged filter, it negatively affects the performance of the air-conditioning and heating systems and makes the components work harder, leading to a shorter useful life.

The technician who looked at your vehicle is most likely correct. Make sure that your cabin air filter is checked and changed regularly, based on the manufacturer’s recommendation.

Warren McCord is an ASE Certified Master Technician and owner of Dean’s Automotive Inc., 2037 Old Middlefield Way, Mountain View. For more information, call 961-0302 or email McCord at This email address is being protected from spambots. You need JavaScript enabled to view it..

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