Long story, but bear with me, as I'm sure there's stuff youz guyz can make fun of me for.
So for the last couple of weeks, I've noticed an odd odor in my 4Runner when I turn on the A/C. Stronger initially, but then got better after a few minutes of running, until this week when it has just gotten worse. For the life of me, I could have sworn the smell was of cow manure, and coincidentally, we had just spread manure on the 40 acres by the house a few weeks ago. My thought was that maybe when I drove down one of the back roads, somehow some manure chunks had shot up from under the tires into the engine compartment, and the odor was going through the vent system. I looked everywhere under the hood and the underside though, and saw nothing.
This morning it was absolutely unbearable. I was driving into town and so did some experimenting. I could smell it fairly strongly with just the vent on. Much stronger when the A/C was on. Then I turned the heater on full blast and got no discernible smell. Then I got home and Googled. There were lots of posts regarding mold, etc. and how to get rid of it, and then also some about, "first try to replace the cabin air filter". Aha! This is the first vehicle I've owned with a cabin filter, so I had completely forgotten about it. I only have a tad over 10K miles though, and normal replacement is listed as 20K, so I didn't get all excited that this would do anything. I figured, "Let's check it first, and see what it looks like." Well, I checked it, and refer to the image below:
My first thought was, "This looks like a mouse tried to make a nest". But how the hell would a mouse get into the cabin air filtration system? It seemed impossible. Plus there was no dead mouse in the filter, so what the hell? Nevertheless, the filter was obviously a mess, and I detected the odor I was smelling in the cabin. So in too much of a hurry to order from Amazon, I ran into town and let myself get gouged for a $15 Chinese filter.
So now I'm ready to install the filter, but the filter instructions say, "point arrow down in direction of airflow". That didn't seem right, so I checked the manual, which said, "Point arrow UP in direction of airflow". Okay, who's right? Only one way to find out Ben - turn on the engine and stick your hand in the slot to see which direction the flow is going. Which is what I did. And then this levitated up above the fan with the air pressure:
So it was a freakin' mouse after all, but I still have no idea how he got into the cabin filter.
Anyway, I replaced the filter, sprayed some Lysol down the intake vents by the windshield, and let the car run with the A/C on for 15 minutes. The smell is already pretty much gone. Now I'll let it sit overnight and check again tomorrow to be sure. You can be sure that I'm going to be checking that damn filter every 5K miles from now on, and for as cheap as they are, replacing the dang thing annually.
But this brings me to my actual question: Is there any big variability in these filters? I see an array of them on Amazon, some simple "OEM replacements" and others touting charcoal filtering. I know that charcoal elements can make a big difference in household air purifiers (I have a couple of them), but are they worth the extra money for a vehicle filter, or is it just better to replace the cheaper OEM filter more frequently?
