What is a cabin air filter? (and why you shouldn't forget about it)

What is a cabin air filter? And how important are they, really? I mean, they only really became a thing in the late 90s, and we were all fine before then, right? Well, you know how old cars always smell a bit funky, and new cars don’t? That’s thanks to the later vehicles’ cabin filters.

They’re there to do what it says on the box and filter the air that flows into the cabin. Take it from a guy who once did a Simpson crossing in an old Troopy and was coughing up red dust for three weeks afterwards; they’re a good thing. They protect you and your passenger’s lungs from being contaminated by the outside air. It may not sound like a big deal, but with ever-increasing levels of dust, smog and air pollution, it’s nice to know that the inside of the four can offer some protection from the outside world.

With that said, they’re almost always overlooked when it comes to service time. The oil, fuel and air filters are checked and changed religiously, but for some reason, most of us neglect the cabin filter. Probably because most folks don’t know where it is or even that they have one.

The anatomy of a cabin filter

Similar to an engine air filter, a cabin filter is made up of pleated and coated engineered material or multifibre cotton that allows air through but traps harmful contaminants like pollen, mould and smoke. They’re a barrier between the inside and outside of your vehicle. In addition, all air for your HVAC (heating, ventilation and air-conditioning) system will pass through the filter.

New tech

As with all filters, companies like Ryco are constantly developing newer and better means of filtering the cabin’s air. Their latest innovation is the N99 Microshield, which is incorporated into their existing cabin filters.

The filter has particle and activated carbon media layers that block airborne chemicals such as ozone and exhaust gasses, as well as neutralising odours. Then, the air passes through the N99 medical-grade media, which removes up to 99.7% of airborne bacteria and viruses and filters the contaminants down to less than 0.3 microns.

Basically, if we were all wearing these cabin air filters on our faces, COVID-19 would have been a lot less of a hassle for everybody. Just saying.

Filter maintenance

The problem with cabin air filter maintenance is that most folks don’t know where they are. There’s no big obvious airbox to crack open or an oil filter housing front and centre to put a socket on. With that said, most are still pretty easy to find. As a barrier between the outside world and the inside of the cab, they’re usually housed somewhere on the firewall, most commonly behind the glovebox.

Pretty much every quality cabin air filter comes with instructions specific to your vehicle. However, swapping one out often involves whipping the glovebox out (2-3 screws), opening up the filter housing (catches or a couple of hex-heads), pulling the old filter out, being careful not to shower yourself with dust and old leaves after leaving it way too long, slipping the new on in place, and reversing the procedure from there. It’s a five min job. Tops.

Check out the video below for how to change your cabin air filter …

As for how often? Ideally, you should change your cabin air filter with every engine air filter change or every 15,000km or so. Obviously, this will shorten up significantly if you’re a regular bush driver or park your car under a tree with a billion small leaves that it likes to shed regularly.

Also, don’t scrimp just because it doesn’t filter your engine. Get a quality filter that will remove odours, pollen, mould, dust, and dirt. Your lungs will appreciate it.