Stuck Ventilation Lever
After the interior went back in I realized that the passenger ventilation lever was partially stuck. In turn I concluded that this was the reason the air conditioning was not getting things cold. No alternative but to start disassembling the center console again. Thankfully on the 308, that only requires removing two screws hidden in the ashtray.
Once the reverse side of the lever was visible, the problem was apparent. The cable sheath had slipped out of the lever body so the cable was no longer pulling the flaps at the front of the car. In fact it was snagging on the dislodged sheath, limiting the movement of the lever.
Repositioning the cable and tightening the cable clamp was a simple fix.