How does cabin air filter work in your car?

Many people may see "replace cabin air filter" in their car maintenance bill, but only a few people know what a cabin air filter is. So, do you really know what you paid for?

What are cabin air filters?

Cabin air filters, also called "activated charcoal filter", "dust and pollen filter", "air conditioning filter", or "passenger compartment air filter", are just like masks you wear or furnace filters you use at your home, but they are for your vehicle. It cleans the air entering in to a vehicle's cabin. Due to the air pressure, there are tons of air flowing into the vehicle through the ventilation ducts during driving. It may contain around two to five times more pollutants, car exhaust, construction dust, pollens than the air by the side of the road. Therefore, every car has a cabin air filter to block the majority of dust, particles, pollens. In addition, it prevents the ventilation system from clogging, and protect the auto HVAC system. The cabin air filters are usually placed behind the glove box or under the glove box where drivers could easily accessed. 

How to choose the cabin air filter for my car?

There are a lot of brands and materials of cabin air filter to choose, but the most important thing is to find the correct filter that fits your car. The majority of automotive parts websites have search bar, you can simply enter the year, make and model of your car to find the corresponding filter. In addition, you could check your filter's dimension, and the number on your existing filter, which is the OEM number, to see if they are matched the one you find on the website. 

Then, you could choose from the different materials. Normally, there are three different ones.

1. Particle cabin filters: they are usually white and made of paper. Can block 99% big airborne particles, such as dust, pollens, dander.

2. Activated carbon filters: they have at least one layer of activated carbon. Compared to particle filters, they also provide deodorizing agents, absorb musty odors. Thicker the activated carbon layer, higher the absorption function. 

3. Three-layer filters: in addition to the above kinds, three-layer filters like FreshenOPT have higher filtration, and provide protection from allergens and mold. The premium quality ones also offer supporting layer which could prevent the deformation of the filter.

When to replace? 

If you notice one or more of the following signs, it is likely that the time has come to change it.

1. Reduced air circulation inside your passenger compartment⁠

2. Diminished heating and air conditioning performance⁠

3. Musty odor in the cabin of the vehicle⁠

4. Cabin air intake ducting may begin to make an unusual whistling sound⁠

We recommend to replace it every 10000km or 1 year to get optimized freshness in your car. However, it depends on the driving environments. If you don't drive your car too often, you may changed it less frequent. If you drive in heavy traffic in an urban area that has poor air quality, you could need to replace the cabin air filter annually or even more often.