When I installed aircon in my humble 200B years ago, I checked the parts book to see just what parts were involved.

One of the parts that the factory thought was necessary enough to produce was a rubber strip that sealed the gap between the bonnet/hood & the top of the radiator support panel.

I knew full well that if the factory could save 5 yen per vehicle by leaving it out & still have the aircon & the cooling system perform as advertised, then they would leave it out in a heartbeat, so clearly it was regarded as important & I found one in a wreck & fitted it.

Those Datsun engineers were not known for being stupid so I figured if it was good for them, ................................