Welcome!
The K40 Intro linked to in the header is a summary article with lots of advice that links to other pages with more advice. Among them is this gem:
Added Power Supply
The K40’s stock power supply is adequate, just barely, for K40 operations. If you add stuff on (like LED strips for strips for viewing the lasing through the window while engraving, or for better visibility to set up stock to work on) it may cause issues because the power supply is just barely able to put out the power required without those additions.
A fan will draw substantially more power than a few LEDs, generally speaking.
It sounds like you are trying to use fans for air assist. That’s probably not the best route. That same article has a better suggestion for air assist, to use an aquarium pump. They come in different capacities, but even a tiny aquarium pump will be better than fans, which would be basically useless.