The third skirt fan placement for v2.4

[grim estuary]

I got a leftover 80mm fan from the kit as I didn't use back filter. I don't think I will have any use for it.

But there are two location that I could install the fan. Where should I install it? In which direction?

Only back skirt are solid.

Those two green circle are empty fan mounting location. reds are installed fans.

mcu got its own dual 6010 fans and pi is in armor case dual fans version.

[humble tapir]

looks like your cooling setup is already more than adequate

if i were to add the fan, i'd locate it in one of the green circles so that it's sucking air out to keep the airflow from right to left of your image