Recirculate is always on for me, too. I just turn it off for a few minutes when the car was left in the sun and the air inside is very hot. I let in fresh colder air from outside since usually nasa open parking ka pa nga lang. Minsan tumatakbo na sa daan ang sasakyan na nakakalimutan ko i-ON then mangangamoy usok sa loob (or pag minamalas-malas, amoy basura) doon ko lang maaalala na-off pala yung recirculate. Yung iba pang reasons to turn off recirculate eh nabanggit na rin naman sa itaas.