This is the element for the Kada 852D, there looks to be 4 wires. I assume 2 for power and 2 for the thermocouple.
Whether or not the thermocouple is connected and monitored is another matter, it would be interesting to see one in a tear down.
yes it is monitored, the same to iron. after turn off, the gun still on until the temperature down at some setting then automatically off, there's magnet in the gun seat to automatically shut off fan when placed on the seat. mine is 852AD+, with gun and iron heaters + tips spare part included. no need to replace yet, hopefully for a long time, about a year old now, but not frequently used esp the gun (fan in the gun, not in the body). the only issue with me right now is some kind of lose connection that iron temperature display sometime showing wrong numbers, hammer it then its ok. but temperature monitoring/regulation is actually working behind. once it got worsen, i'll do the surgery. but so far no need.
about that video, i saw that before i buy this station year ago. i dont expect china product to last long. but this one i can give thumb up (only one thumb, not two), and i would not recommend other to buy. i prefer hakko station (iron only), the black colored one (old model), not the blue toy colored new model
and my story above is just 10% of all. imho, whats 90% most important, is the original branded solder
tip, mine is not original sometime i got pissed off (solder dont stick well and coating not so durable). even if you buy china station, make sure you get hakko original tip. this kada 852 is compatible with hakko tip, good news there. i will get a couple hakko tips when i'm stable. but what sux about hakko, is they only available from US. shipping the tip will cost nearly to buying the complete station, so that sux for me asian.
ps: i prefer fan in the gun. i can see thats just a small fan, but strong enough to blow big chip away. if damaged, easily replaced with small pc fan. but for diaphragm fan inside body, if its broken, its nowhere to be found. and the gun (with fan) cable wire is small and easy to work with. diaphragm got a big pipe going out to gun, i imagine that can be stiff. but i dont know, i never touch that pipe.