355 a/c recirc & transaxle filter cleaning ?

I've got a '99 355 f1 spider.
First issue i don't understand is the recirculate function only works with the a/c stop buttoned depressed. As soon as i release the stop button the recirc door swings down and is longer active with the recirc. button. Is this a normal function, i hope not. I would like to have the a/c recirculate the cold air..
Possible fixes.

Second
Does anyoune clean the filter in the gearboxes when doing the oil changes in them. i'm planing on doing a oil change in the near future. Need to know if i can get to it and do i need some replacement gaskets..