Reefers always have lots of gears in aquarium cabinet, working gears generate lot of heat, especially you have a chiller inside. A well circulation of air brings you lots of pros by just adding a fan.
Here is my case. Two return pumps, protein skimmer, media reactor, ATO pump, 30W algae light, the temp of cabinet is around 30C which is good.
While chiller is working, the temp of cabinet is raised up to an unbelievable 65C/150F which might kill several thousands gears after few weeks later. Most important of all, I don’t want to get close to my tank any more, especially maintain the tank turns me a blacksmith working in forge.
I put the magnetic temp probe attached on metal case of modem and config teffo to trigger cabinet fan on @25.8C to improve the circulation of air.
Don’t waste the rest three sockets, I connect them with NP reactor (w/ schedule), ATO pump and algae light (w/ schedule). It’s easy and useful to manage those at once.