Replacing your cabin air filter is a rather simple and easy part of vehicle maintenance, but it is also one of the easiest to forget. While newer cars remind us of basic maintenance like oil changes, other forms of maintenance can fall through the cracks. Luckily, old, worn-out cabin air filters are almost as easy to diagnose as they are to replace, and it is one of the least expensive pieces of your vehicle’s air conditioning systems to change in case you aren’t getting the air quality you want.

The air coming out of the vents is starting to smell funky

Funky is a rather arbitrary term when it comes to describing scents, but if you’ve ever had an old air filter, it isn’t hard to identify the musky scent of an old, worn-out air filter. Of course, there are several reasons why your car could smell musty — such as a spilled beverage on the carpet, old beach towels, or a forgotten gym bag. But, if the smell is coming from the air vents, it is pretty distinct, and that could mean that it’s time to replace your cabin air filter. This is the most common issue that owners face when your air filter is past its time for a replacement.

Your air conditioning system sounds louder than it did before

You aren’t going crazy — if your air conditioning system sounds like it’s blowing louder and harder than it has in the past, it could be a sign that your cabin air filter is in need of replacement. This increase in noise is caused by the air conditioning system has to work harder to provide sufficient airflow, which happens when the airflow is blocked by a clogged or dirty cabin air filter. If you don’t have the filter replaced, it can cause unnecessary strain on your car’s air conditioning components, such as the AC blower motor.

The cabin air filter is preventing adequate flow to the cabin

In the summertime, it can feel like our air conditioning system is never blowing hard enough, but there is a chance that it actually isn’t. Because all of the air being brought into the cabin through the system is pushed through this cabin air filter, an old, dirty, and clogged filter can prevent efficient airflow. If it’s been a few thousand miles since you checked on your cabin air filter, decreased airflow is typically as easy to diagnose as replacing your filter — which is one of the quickest and easiest DIY tasks even novice car owners can tackle.

Replacing your cabin air filter can take just a few minutes and be relatively inexpensive, but if you don’t recognize the signs of a fault, dirty filter, you can be compromising both your air quality and straining your vehicle’s air conditioning systems. While maintenance suggestions by mileage can vary between a vehicle’s year, make, and model, the general rule of thumb is to change it — or at least check it — every 15,000 to 30,000 miles depending on the climate and air pollution of the area you live in.