Dropbox fan doesn’t come on

I replaced the fan in my 5D and thought everything was fine, but after a couple of minutes, the drone would power down and the drives were very hot. Investigating, I found that on plugging in the power, the fan would come on, but then switching on the Dropbox, the fan would switch off - never to run again.

I suspect that the fan controller is broken - but does anyone know where that is? I assume it is near the drives, but can’t see anything resembling.

For the meantime, I just hotwired the fan to 12v so it is on full and continuous - so rather noisy!

Could it be you have a bad connection, or wired the fan in backwards? Otherwise your hotwire may be the best option.

In this link I mention the fan needed for Drobo 5N. I believe the 5D is similar. Perhaps the fan has specific volts/amps/startup requirements that standard PC fans do not.

The fan is 12v dc, wiring it the other way round will still make the fan move, just in the wrong direction! Anyhow, I put the old one back in with the same result - fan switches off when the Dropbox is powered on (but runs when plugged in and switched off).

The hot wiring is OK, but is pretty noisy (I still have the old fan in). I’m getting a new one (the original part), so hopefully the noise will be less - even though it is continuously running.

Ideally, I’d prefer to fix the heat sensor if I could find out where it is!