I have been working as a technician now for 20 years and I certainly have grown some pet peeve's about vehicle maintenance. One of the more important parts to change frequently for me is the cabin filter. I don't have to tell you that our bodies like our vehicles engine work better with fresh clean air. Change your cabin filter more frequently than your vehicles air filter. You will notice the difference.
Here in California and many parts of the country we use our A/C and heaters in our vehicles frequently. With that reason alone we should be concerned with what is going into our lungs and blood stream. An A/C evaporator and the heater core which are the units inside the vehicle where the freon and hot coolant passes tend to go through rapid and frequent temperature fluctuations. That attracts bacteria and allergens coming from the outside which form mold and spores. That is why some of us complain of a stinky smell coming from our air vents. With a fresh clean cabin filter in your vehicle it reduces the amount of harmful bacteria coming into the cabin and into your lungs. Not only does a cabin filter protect you but your A/C and heating systems from premature wear and expensive repairs.
Most cabin filters are located in the cowling near the front windshield, behind the glove box or just underneath it within the air box. Once you access the filter, see if it looks dirty. If it does not, tap it slightly and see if dust or dirt shake out of between the filter fibers. Either way, your filter should be changed as a good practice every 15,000 to 18,000 miles or sooner if you drive in extreme conditions.
If you don't know if your vehicle has a cabin filter consult your owners manual. 85% of vehicles built in the last 5 years have some type of filtering into the cabin. If you still don't know, consult with us and we can advise wether your vehicle has a filter located in the climate control system of your cabin.