I noticed something weird on my new 2002 LS430.

The airflow selection switch often sets itself to non-auto recirculate when I first start the car eventhough I left it on non-auto outside air before I turn the car off. Does anyone know why? Is it suppose to do that even when it is not on auto mode?

 

idiot engineers do that.

If your car is hot or warm when you get in the idea is to first cool the over-heated interior air rather than first bring in cooler air from the outside thereby purging the over-heated interior air.

When my Lexus does this I try to remember to quickly over-ride it to flow-thru mode, turn the blower up a bit, and maybe lower the rear windows slightly. After the interior atmosphere's temperature is reduced to at least that of the outside world then I switch to recirc to get quicker "cool down".

But always remember to put the system back into flow-thru and run it that way as much as possible.

 

can you please explain to me why? i have a habit of always keeping it in recirculate.

 

In flow-thru the cabin atmsophere is being continually replenished, no stale odors, no high humidity, etc.

Most cars automatically switch to flow-thru in defog mode to help quickly get any accumulated humidty "out".

The more people you have in the car the more it is necessary to use non-recirculate especially with respect to keeping the windshield defogged.

 

oh i see. i just hate the exhaust fumes that leak in sometimes though. oh well. thanks for explaining.

 

Keeping the airflow consistently in recirculate is much more harmful to your health than smelling and breathing the exhaust fume sometimes. Besides the CO2 buildup, which can cause one to be sleepy more quickly while driving, the moisture often causes mildew and the fungus particles can cause some serious allergic reactions for some people.

It's too bad that the stock air filter is not HEPA or active charcoal. I wonder if there is any aftermarket HEPA or active charcoal filters available. I had it in my MB E320, it worked very well and filtered even most of the odors from the outside air.

 

Also, mold is known to collect in the duck work of A/C systems. The non-recirulate helps keep mold and odors from accumulating.