I obviously need to block this, but I'm trying to figure out the purpose of the hole - is it important to allow airflow?

On LEAFs equipped with heat-pumps, that is a pass-through for lines to and from the "inner condenser" Iirc, S-model didn't have the heat pump so it was probably just blocked off. I don't know if that part of the plenum would be under fan pressure on an S but since it's now open you can check with the fan on high. If you feel air blowing out then make sure to seal it in such a way so that blower air does not escape.maxmelchior wrote: ↑Sat Jan 02, 2021 10:35 amDoes anyone know the purpose of the hole? Or where I could look it up?