We often get vehicles brought in that smell of burned leaves, mildew and cat hair. While these are really pleasant smells for any occasion, I'm certain that there are other odors that might be more appealing. But, before we get to the more aromatic wafting of air, we should talk about why your car smells this way. It's quite possible you engaged in an act of self-sabotage. As you are well aware, a shop may have tried to sell you a cabin air filter to which you replied "I just changed that last week!", not knowing that engine air filters and cabin air filters are not the same thing. Or maybe you did know the difference but thought: that filter isn't important! But, actually, it is important, and unlike some repairs on your car, you'll likely see an immediate difference with this one.
If you took a look at the picture at the beginning of this post, you'll see that the cabin air filter we pulled out of a customer's car is filled with debris: leaves, dust and all kinds of other junk that flowed into the cowl and vents on the outside of the car. The cowl will catch most of the large items but some sneaky guys will get through. When you turn on the air conditioning or heat, the car is supposed to bring in fresh air from the environment that runs through this filter to give you healthy doses of oxygen inside the cab. Bus, as this air is brought in so, also, are all the external elements. These elements can burn up, break down or grow and bring on the funk.
Changing a cabin air filter is typically an inexpensive investment. Many car owners decide to, in fact, do it themselves. Most car makers have made this easy to do and the biggest headache is clearing out the glovebox to gain access to the filter. But, there are a few warnings to take heed of. We've seen a number of glove boxes that have been broken when they were reinstalled incorrectly; we've also seen trash inadvertently get dropped into the blower motor that lies beneath the filter, resulting in noise and failure of that part. While a cabin air filter is cheap, a glove box or blower motor isn't. So, be sure to use caution in this instance and if you feel reticence, just leave it to the experts. There are also some cabin air filters that are a PITA, so make sure you fully understand what you are getting into before ripping stuff out. It's a real downer when you get half the dash pulled apart only to realize that it's one of those filters you get to from the engine compartment. Either way, plan on changing this filter every 15,000 miles. Since you can't see it without removing it, it's critical to keep track of its history. But, anyone who has to drive with you in your car will be thankful you swapped it out.