Lower fan works only at end of print?

Is it normal that the lower fan only kicks in near the end of the print? (eg with glass-t)

No, it start running after the raft was done (autofan).

Maybe the "end" of your print is a small area and then the fan speed is increased. So you can ear it running at this time.

I check,during part printing,  if the fan is running with flash light directed to it.

My 50 cent

You can check during the print by small piece of raft inside, it won't damage blades. 

ok will check this. I did change the fan with the spare that was sent me, but so far the prints were not better.

ok will check this. I did change the fan with the spare that was sent me, but so far the prints were not better.

what duo you means but your print are not better. Have you got pictures?