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First-Person Single: Cabin odor got you stumped?

Dirty cabin air filter...full of leaves and debris. (Credit: Hub Pages)

If the inside of your vehicle smells like an old sock when you turn on the air conditioner, it might be time to change the cabin air filter.

“The what?” you say.

I know! It’s all I can do to remember there’s an air filter for the engine…Who knew the interior had a filter, too?

The filter on the right is the one I want the air I breathe to blow through. (Credit: Hub Pages)

Today, some 40 percent of vehicles on the road have cabin air filters, and 80 percent of all new domestic and import cars are so equipped. The OEM filters are usually paper filters, which trap large and smaller particles like dust, spores, pollen, bacteria and other airborne contaminants.

Newer technology offers us the activated carbon (charcoal) filters, which absorb unpleasant odors and gaseous compounds in addition to the particles.

And here’s a shocking statistic: The air inside a vehicle can be six times more polluted that the air outside it.

Now that you know your car has a filter for your interior air, it just makes sense that over time it would be less efficient as it becomes clogged with dirt. Add in the moisture from our humid southeastern Pennsylvania summer and the filter (and the air blowing through it) becomes musty as well. Or, if you’re going by your nose, “damp workout clothes meet dirty sneakers.”

Inserting the clean replacement filter under the hood beneath the dash. (Credit: 2CarPros.com)

Since clogged cabin filters put a strain on your heating and air-conditioning systems as well as seriously impacting the air quality inside your car, experts recommend replacing your cabin air filter every 12,000 to 15,000 miles, or once a year – more often if you typically drive in dusty or smog-filled environments. If you have a carbon filter that absorbs odors, you’ll want to replace it sooner when you notice an “off” smell.

(I’m not even going to talk about smokers who light up inside their vehicles, except to say “Knock it off right now!”)

The good news is that replacing the cabin air filter takes less than 15 minutes in most cases. Most are located under the hood, behind the glove box or under the dash. If you have just gone to the glove box to look this up in your car’s manual, the filter might be referred to as a passenger compartment filter, interior ventilation filter, pollen filter or dust filter.

And if you want to be proactive about it, here are some tips to keep your cabin air filter in its best shape longer while protecting your air-conditioning system:

  • Turn off the a/c when you go through a drive-thru carwash (or set the vents “closed” to “recirculate”) to keep the jet-sprayed water from splashing into the air-conditioning system
  • By limiting your use of the “maximum” setting on your a/c and changing it to a lower setting shortly before turning off your car, you give your air conditioner a chance to dry itself out. By not leaving odor-causing moisture inside the system, it helps prevent mold from developing.
  • A temporary fix is to spray a disinfectant directly into the vents around the windshield area on the outside of your car. Then run the air conditioner for the first few miles on “outside air” (vents open) before switching to “recirculate.” The stronger inside airflow flushes the disinfectant through the system.

Just a note: If replacing your cabin air filter doesn’t eliminate that musty smell coming from the vents when the a/c is running, it is possible mold or mildew has built up inside your system’s evaporator. Ask your service advisor which Fred Beans facility offers air-conditioner odor service that can clean up this problem. The process usually uses a chemical foaming agent to remove the mold and mildew and leave your cabin air smelling fresh – while saving you from the risk of damage to your “personal interior air filtering system”: your own lungs and breathing passages!

And another note, even more important: Cut-price filters and/or replacement services may also be delivering cut-rate quality. Just because the filter is clean and new doesn’t mean it will do the job you are expecting it to do. Make sure you trust your mechanic and the parts he/she uses.