Solved When should heat sink fan come on?

Question: When should the smaller hotend fan (attached to hexagon heat sink) come on? I know it should be running at all times, but starting when? When you click "Start", or when you power on the machine?

I haven't tried printing yet, but I'm afraid to (new hotend installed) because the fan is not currently on, after powering on and preheating... I'm wondering if I have to press "Start" to turn on the fan, or if I have a bigger problem here... (which may have caused my jam and leaking in the first place)

Where does that fan attach? I can find all of the other connectors, but not the one for that 25mm fan

 

And... the nightmares continue. Troubleshooting this printer is going from bad to worse.
From what I can tell, that hotend fan is supposed to come on when the printer powers on. It doesn't. So... what now?

Well, if RoBo 3D hadn't made the idiotic move to run the fan wiring alllllllll the way down the corrugated plastic tubing and into the sealed-off board underneath, maybe it would be an easy fix. Of course, every other component seems to have a clip-terminal right there and easily accessible (heater, thermistor, 40mm fan)... but no, they couldn't have made it easy for me to just swap out another fan to try a new one (assuming that's the issue -- who knows. Could be the board? Could be the wires?)

What a nightmare. I replaced the hotend ($50 or so), but still can't use the machine because the fan is dead (also, I really don't like these aluminum heater blocks for the hex hotends... had another stripping problem with a hotend new out of the box, this time when inserting the screw-in clamp for the heater; other metals would force alignment if the threads are not lined up perfectly, but this aluminum is so soft it just yields instead. I've built a theremin from scratch, and been remodeling an entire basement with no stripping or threading issues... yet I'm 0-for-2 with trying to screw anything into the hex heater block)

 

I'm concerned that you had 2 failures. How are you assembling this?

Fans usually plug in here:

 

I would request a new fan. I had the same problem. My hot end fan was working intermittently. New fan shipped quickly and I'm back up and running.

http://www.robo3dprinter.com/pages/replacement-part-request