Not that anyone in most of Oz would notice if there wasn't coolant flow.
When I bought my Neo, that whole coolant path was completely blocked with solid crap. I had to dig it out so that I could bleed the cooling system properly, but until I did, I never struggled with idle control. We're not in Idaho.
IACV has an air bleed plug in this part of the engine manual. I'm guessing if it isn't bled it will cause weird idle behavior as the cold start valve won't get hot enough to close properly at the usual rate.
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