Remove the left rear side trim panel.
Remove the BSI control unit (A).
Disconnect the BSI control unit 16P connector (B) and detach the harness clip (C).
Remove the bolt.
Install the BSI control unit in the reverse order of removal.
Honda Odyssey Service Manual > Rear A/C System Description: Rear Heater-A/C Door Positions HOTCOOL(VENT)(HEAT/VENT)(HEAT) ...