Air conditioning filter

Yeah, well there's that, too...

 

Perhaps it's just me, but I'm confused why there are 2 buttons which seem to perform the same function (I've copied the descriptions from the owners manual below). The only difference seems to be that the micro dust and pollen filter button directs air to the upper body & turns off automatically.

Also, the manual refers to the filter behind the lower glove box as the air conditioning filter--not a micro dust and pollen filter--leading one to believe there are 2 different filters.

Switching between outside air and recirculated air modes
Press .
The modes switches between (recycles air inside the vehicle)
and (introduces air from outside the vehicle) modes each time
the button is pressed.

Micro dust and pollen filter
Press .
Outside air mode switches to recirculated air mode. Pollen is removed
from the air and the air flows to the upper part of the body.
Usually the system will turn off automatically approximately 3 minutes
later.
To stop the operation, press again.

 

I wonder about the statement that says, "Usually the system will turn off automatically approximately 3 minutes later."

This implies that sometimes it does not turn off in 3 minutes. So what is it's criteria for turning off? Does it have someway of measuring pollen and dust and turns off when it's removed some predetermined amount?

 

I think the distinction is in "micro"--it's much more dense, not designed to run all the time. It is effective in my other car (Lexus) when odors or dust are really objectionable. There's no way to prove whether it removes dramatically more pollen or dust, but an earlier post indicates it's an in-demand item in Japan where hay fever is a big issue.

 

So it's a different filter than the A/C filter? That's what I'd infer from the owners manual.

 

I recently replaced my 09 cabin filter with a Fram Fresh Breeze that contains charcoal and baking soda. Amazon had a good deal on them. Fram claims 98% of contaminants in the air passing through are filtered removing dust and pollen sized down to 5-100 microns. Some pollen irritants may be smaller.
I changed the filter earlier than OM called for hoping to make a difference in my auto's air quality. It might have...asthma is not an issue for me at this time so I can't the tell impact on that condition.
This is inexpensive, easy to change, and might help when your son is in the car with windows up and fan running. Some recirculation might not be a bad idea as well.
Good luck, my daughter had asthma and I know it can be a real problem.

 

That's my impression. The Lexus manual describes it no better--actually about verbatim, but that micro filter does have an effect on bad odors when you select it.

 

I think the missing piece is that the filter button not only put the system in recirc. mode (and change mode to Face) but also makes the fan run faster.

Here's my logic:

In auto mode, when the desired inside temperature has been reached, the fan spins very slowly. Simply switching to recirc while staying in auto mode wouln't help removing pollen from the inside air as it would take too much time.

So, yes there is only one filter, yes outside air is always filtered. All the filter button do is switch to recirc, makes the fan run faster to clean the inside air faster and change mode to let the filtered air be used by the passengers as soon as possible. After some time (3 min.), it revert back to auto and the fan slows down.
You could all do this manually but you would need to press many buttons, at the beginning and at the end.

 

Here's a post from the Club Lexus Forums on the IS, and it appears to shed some light on the micro dust and pollen filter. The source appears legitimate (IS 250/350 Product Intro Brochure, displayed in the post)

"Info courtesy of Lexus College Page 38....

5. Micro dust and pollen filter
a. std all models
b. increases portion of RECIRC air
c. driver selectable"

I guess it's just a higher percentange of recirculation, since I believe normal RECIRC is something like 80% recirculated/20% fresh in most cars to deal with potential CO entry.