We all know vehicles these days are loaded with the latest technology and gadgets, from active safety features such as hill-start assist to cupholders that heat and cool. But did you realize your car also has cabin air filters that keep the air fresh for you Without this nifty car part, your car cabin would fill up with every smell and noxious fume you come across on your drive. Cabin air filters are essential, and so is knowing how often to change a cabin air filter.

How often to change an air filter in a car

The best place to find this answer, which differs per manufacturer, is in your vehicle's manual. Some will recommend every 45,000 miles, while others recommend closer to the 25,000-mile mark. And there are some companies that will even recommend you replace the cabin air filter every 15,000 miles if your driving conditions include heavily trafficked roads, high heat or dusty, unpaved road conditions.

Gregory Prokopenko, the chief mechanic at Momentum MotorSports in Quebec, Canada recommends a yearly change at minimum.

“I suggest to clients that the air filter be changed once per year and inspected every service,” Prokopenko said. “For areas that have high dust or harsh winter conditions, that interval can go up to two or more per year. You don' t want to be losing performance or fuel economy. It also can get to the point where the filter is so dirty that particles start making their way into the engine and causing possible damage.”

Signs you need a replacement air cabin filter

There are some telltale signs that will indicate it's time to replace the air filter in your vehicle. It's not just about bad smells, and if not replaced in time, a bad filter can actually damage your vehicle. If you notice any of these signs, replace your filter ASAP.

Weak ventilation airflow

One of the first signs you need to replace your air filter, and one of the least damaging, is weak ventilation airflow into the cabin. This can be caused by buildup on the filter itself—this is common if you drive on dusty roads or live where there is an increased level of air pollutants such as pollen. If your air conditioning is blowing weakly even at the highest fan setting, the filter may be clogged.

Strange odors

Another common sign that your air filter needs to be changed is when you notice odors in your vehicle. The idea of ​​having the cabin air filter is to protect the occupants of the car from particles and smells outside the car—the moment those start seeping into the vehicle, the filter has lost its efficacy. Also, pay attention to the mustiness of the air inside your vehicle when the vents are on. How clean and clear is the air?

Increased dust

If you always drive with your windows closed but you notice a layer of dust or pollen slowly beginning to settle on your dash and other surfaces, it might be a good idea to have a look at your cabin air filter. The dust likely means that the filter is so clogged that those particles are making it past the filter barrier and straight into your face while you drive.

A whistling sound or excessive noise from the vents

Pay attention to how the airflow sounds when you turn your vents on in the car. Cabin air filters that are blocked or clogged won't let air pass easily, and that can cause a strange high-pitched whine from behind your dashboard or even cause your AC system to be louder. These are signs the system is laboring and requiring more effort to push air through the filter and out the vents.

Visually looks clogged and dirty

If you have the ability to look at your filter, you will be able to immediately see whether or not it needs to be replaced. You might be shocked to see leaves, twigs and grass, along with lots of dust and dirt. If your air cabin filter looks like that, it is most definitely time to change it out.

What happens if the cabin air filter isn’t replaced?

According to Prokopenko, the air filter is “one of the most overlooked maintenance items” on a car. Because it links directly to the human occupants in the vehicle and keeps the air they breathe healthy, it is an essential part of any vehicle.

If the cabin air filter isn't replaced regularly, you run the risk of breathing in dangerous particles while inside your vehicle. Noxious fumes, pollen particles, dust or harsh airborne chemicals can and will enter your vehicle cabin if you do not have a fully functioning air filter.

Also, the more clogged your air filter is, the harder your HVAC system will have to work; putting unnecessary strain on your ventilation motors and system. This could result in more expensive repair costs down the road. A new air filter is orders of magnitude cheaper than a new air compressor.

How much does an air cabin filter replacement cost?

The average cost of a cabin air filter is between $15 and $50, depending on the size of the unit. Labor fees vary per mechanic and garage.

As is the case with more vehicle parts, the cost to replace items is often dependent on the type of vehicle you 

have. Some luxury brands will charge more for their parts and require that you only buy their branded cabin air filters, while others suggest you can purchase a generic cabin air filter from your local automotive shop.

Some mechanics will recommend you change your cabin air filter during your routine visit to the garage for regular maintenance. That's fine, but make sure you ask to see the filter first. Visually inspect it, and if it looks like it needs replacement, do so . If not, you can always wait for a later date.

How to change a cabin air filter

If you've changed an air filter in your air conditioning unit or air exchange unit or even in your vacuum cleaner, you can likely handle changing the air cabin filter in your car. YouTube may be your best friend in this scenario, especially for specific vehicle models, and your manual will also outline where to find your filter behind the dashboard in your car.

The basic steps to changing an air filter in your car cabin are:

Remove glove box pins. These are the screws that hold your glove box in place under the dash.
Remove the glove box unit. Gently pull the glovebox down and out of its space inside the dash.
Remove the old filter. Be careful not to knock the filter too much as you pull it out of its little shelf. It could cause all the dust and particles to billow out into your cabin.
Carefully clean the air cabin filter housing area. Using a handheld vacuum cleaner (not a shop vac—that would be much too strong), gently clear away any leftover debris and dust where the filter was housed.
Slide the new filter in and replace the glove box.
Most car models made after the year 2000 are equipped with air cabin filters (and some luxury models even have more than one); however, models from before that may not have them at all. Again, a quick check of your vehicle manual should tell you if you have one and where it is located—generally behind your AC system near the glovebox, or sometimes at the base of the windshield, just above the engine bay.

Once you know where your air cabin filter is, it is important to keep the filter replaced regularly so you and your passengers can breathe clean, debris-free air every time you get into your vehicle.