I had similar worries about my K7 DL1000, my fan wouldn't kick in at all.
I took her to my back street fixer, and he said it was one of two things: Fan Fxxked or Temp Sensor.
I changed the fan, which didn't fix my problem, so I changed the Temp sensor, that worked
The temp sensor ( on the DL1000) is on the lower side of the radiator and is the cheapest and easiest repair to carry out.
I would go for that first before buying a new fan.
Although, as said in previous posts 3 bars is the norm.
Good luck