(Okay this isn't really engine tech, but this seemed like the best place to post this. Mods: move this if needed)
Yesterday I went on this 6-hour run which was quite dusty to say the least. I had left my ventilation set to Recirculate so the dust wouldn't get in. Towards the end of the run, I noticed the Recirculate switch would change modes on its own, letting "fresh" dusty air in. I lost count of how many times I had to turn Recirculate back on, but this was happening to all the other FJs on the run. Our guess was that it was resetting because the in-cabin filter was clogged. So on the way back home, I decided to stop by the dealer and pick up a new filter.
This morning, I opened up the glove box to get to it (it's in your manual -- page 178), and found a very dirty filter. Here's a comparison shot:
I had around 4000 miles before the trail run so it couldn't have been too dirty before then. And this photo was taken after I shook some dust off the old filter while taking it out of the holder, so it was much dirtier than pictured. You could hit it with a wet noodle and a pound of dust would rain down from it.
When the recirc button reset on its own, I saw a bit of dust coming through the vents, so I knew there had to be some dust in the system between the air filter and the vents. I wanted to try to flush all that out so what I did was take some compressed air and blow it all around inside the blower assembly:
Also stick your finger in there and rotate the fan blades around so that they all get evenly covered with a blast of compressed air:
Dont make the same mistake I did -- unless you want to get dust sprayed all over your interior, get some damp towels and cover up the vents. Also cover up the side vents too.
I didn't figure this out until I first started blasting away, so I still have some wiping up to do on the interior.
So there you have it -- my needlessly lengthy post for a terribly easy procedure.
