Changing Your Cabin Air Filter
By Courtney Evans
“Air filter? I know what that is. I just changed it when I changed my oil. It helps my engine breathe easy. What the heck is a cabin air filter?” Your cabin air filter helps you breathe easy! It prevents dust and odors from entering the interior of your vehicle.
I think we’ve all experienced foul odors while driving; even with the windows closed. Have you ever driven near a paper mill? How about a pig farm? I think that is an experience you’ll never forget. I’ve often said that I’ve never met a pig that I didn’t like, but wow! What an odor! Of course, your cabin filter also helps eliminate everyday odors such as fumes from other vehicles.
Other than odors, there is another indication that your cabin filter is old, clogged, and on its last leg. You turn on the defroster to clear the window. It is completely ineffective. You turn the blower switch to high, you get more noise, but little in the way of increased airflow. Very little outside air is getting in. Clogged filter. I think it is obvious, even to those of us that need a little bit more time to figure things out, that replacing your cabin filter is important.
Most newer cars have cabin air filters. Most European cars have them. You may have one, two, or even three cabin air filters. They may be arranged side-by-side (in parallel), as in the case of 2 of my vehicles, or they may be arranged one after another (in series).
Finding your cabin air filter
In general terms, filter(s) will be located near the bottom of the windshield and visible with the hood raised. Perhaps underneath a cover or grate. Or you’ll find it inside the vehicle, underneath the dash. Possibly in both locations.
For filters located underneath the dash, you’ll either find it somewhere above the blower motor or it may be between the blower and the rest of the HVAC system components, such as the vents. Twist and contort yourself to look under and behind the dash. Look near the glove box. You may see an HVAC type plastic box with a panel door. This is probably where the filter is. Remember, the system was designed for filter replacement, so it should not be an impossible task to find the location of the filter.
You could consult your owners manual. Nah, that would be too easy and where’s the fun in that?
Or, you could get information from the dealership. You could purchase them there, though, at a premium. The parts department will be able to tell you about the location of the filters and even how they should be inserted.
Another great source for info is your local auto parts store. They’ll have aftermarket filters there. You’ll probably have a choice on the quality of filter as well, with potential savings. They can also tell you how many cabin air filters you have and where they are located.
Replacing the cabin air filters
Let’s start outside the vehicle. This filter is the first defense against dust, dirt, pollen, etc. It is very likely that it will get clogged first. Open the hood. To gain access, you typically have to open a cover or by removing an air intake screen. The cover will held by a metal rod, screws, or plastic fasteners. The plastic fasteners are fragile and may have become brittle as a result of sun exposure. If they break, you can find replacements at the auto parts store as this is a common occurrence.
Once you’ve opened the cover, remove the filter. Make a mental note as to the filter’s orientation. What I typically do is compare the new filter with the old. Use your shop-vac to carefully clean inside the filter holder as well as the filter grate if applicable. Make sure that you reinstall the new filter with proper orientation. Some filters have a rubber gasket surface for proper sealing to keep moisture (rain) out. If the filter is not inserted properly, it could get soaked.
For the in-cabin filter, its most likely located behind or above the blower motor. Removing the glove box may be necessary. You can find the screws that hold it either underneath or inside the glove box door. This will require a little diligence. Be careful and don’t loose any screws.
The filter may also be located inside the blower assembly. If you see a door with either clips or knobs, this is probably where the filter is located. Open the door and slide the filter out. Some filters may require bending for removal and installation. Typically, the filters are flexible so this should not pose a problem.
Types of filters
There’s basically two types of filters that are used in cabin air filter applications, particulate only and particulate with a charcoal layer. The particulate type filter is more likely to be found in the air intake or outside the vehicle. This is a simpler filter that is designed to trap small particles.
The more sophisticated filter with the charcoal layer is likely to be located inside the vehicle, behind the blower or glove box. The charcoal layer is used to trap odors and prevent them from entering your nose. This filter may be a little bit more costly but it is definitely worth it.
You should change your cabin air filter every 12,000 to 15,000 miles. I recommend just changing it every time you change your engines air filter. If you live in a particularly dusty or smelly area, change it every 6,000 to 8,000 miles. In my area, the mid-Atlantic, we are subject to a pollen bath during the first 3 or 4 weeks of spring. This stuff gets everywhere and I have allergies so I’m very concerned about pollen. I try to time changing the cabin air filters with the onset of spring. It does seem to help.
Change your cabin air filters regularly to keep your HVAC motor blowing strong and to help eliminate foul odors from entering the cabin. Remember, steer clear of those farms. Unless of course, if you’re a farmer.