Drobo 5N - replaced fan, now only running when drobo turned off

The only thing I did was to rewire / reconnect the connector of the fan, I took off the old one, and replaced it on the new one. The new one had 3 wires, the 3rd one (yellow) I’m not using, so was I told here - what could I have possibly done wrong?

Plus I don’t think the Drobo 5N has a thermal sensor, but I might be wrong.