As far as I can remember, the bulbs are not easily replaceable. You have
to take the ventilation control head out of the car and take it apart to
get to the bulbs. They are not bayonet mounted from the outside like on
the defogger and cruise switches. The Helm manual tells you how to take
out the control head, the rest is up to your ingenuity. Honda probably
does not list spare bulbs for this, you'll have to take the old bulbs in
and hope the parts guy can match them up with something they stock. If
you try to do this at Stevens Creek Honda, the parts guy will give you a
blank stare, then say "Huh? What are those?"