Hey guys...on my Acura 03 TL, whenever i turn the a/c on by pressing the auto button....some times that micro filter button would be on by default (the one where u choose whether u want air coming from outside of car or inside), and sometimes it will be off...is this a problem or this tends to happen when adjusting to hotter or cooler air temp? I noticed this happen more when car is really warm on a hot summer day....thanks

 

when the car senses that the interior is hot, it will recirulate the air to make it cooler faster. it's normal.

 

Yep, SilverUA5 is correct. The car does whatever it can to try and keep the interior temperature to the temp you set. Cooling recirculated air is much more efficient than cooling outside air so when the interior is really hot it will go into recirc mode for a bit (usually accompanied by high fan speed) and then once it cools down a bit it will switch back to fresh mode and drop the fan speed accordingly.