Sure you're not confusing sticky acm's with reluctant pack valves? Does the valve indicate 'open' but the pack is silent? The acm's can be a bitch to get started up first flight of the day - often a bit of apu boost on the eiu (or pulling the zone cntrlr cb's) to get a bit more chuff from the apu & some juggling of pack valve switches will get them going tho'.. .If the pack overheats with the pack valves 'on' its a stuck acm.. .As an aside, if you've got pfcv position indication probs - try a new sdac first. Might save a lot of grief.