That’s what I ended up doing. No issues seen by doing that by I wondered if an air return pipe was supposed to go in there.

My XC60 has this square opening through the firewall in the driver’s side footwell. Cold air will blow out of it sometimes, especially if air is set to recirculate. Not that big a deal in the summer but pretty annoying in January! It looks unfinished, as if something was supposed to go here. If anyo...