Ive delt with the same problem that you are dealing with for the last 6 months. It ended up I had not radiator fluid in my radiator and I filled it to the top and I have had no problems in the last 2 weeks. I re-filled the container all the time but never thought about the radiator.

You should also (forgot the name) were basically you drain the water and fluid's out of the radiator/engine about 4 times and that could lead to the problem.


**EDIT** I was gearing that post more towards other reasons it would be overheating. Nothing to do with the fans.