Interior filter Mercedes W126

Hello 126 friends, I wanted to change the interior filter of my starship for a long time. Unfortunately, I can’t find any information about it on the internet. I’ve even read that I shouldn’t have one, but only 126 with climate. I don’t have a climate in mine. But I have to have an interior filter. The maintenance booklet also says: every 120000 km the activated carbon filter is changed. Is that the same or? Where does it sit in the vehicle? Thank you for your contributions! MfG SirQuickly