But from what I've read, bleed air from the engines is used as trim air downstream of the packs but some of this bleed air also goes to the pack where this air is mixed with the cooled air from the ACM, within the pack itself, downstream of the water separator.
This doubt cropped up when I saw that my refrigerator had no 'trim air'. But it still produced the commanded temp. So why not so in the air conditioning system
