I had a fan problem on my old 9000CS, fan didn’t kick in when it should. Checked the fuse, coolant level, thermo-switch and they were all fine. Checked the supply to the relay, no voltage, so I assumed there was a break in the supply wire to the relay, nightmare of a job if you wanted to do it properly. The supply to the relay is permanent (not through the ignition, otherwise it wouldn’t run after turning the engine off). I settled for a new 12v supply from the battery to the relay, with an inline fuse of course.