Radiator fan not running

I have a 98 old achevia, 6 cly. About 140000 miles,

What could be wrong-coolant light will not go out. THe Hot/Cold hand goes over gradually from cold to hot, can probaly drive about 5 to 10 miles before it goes over to hot.
I have put coolant in for the pass 2 weeks or more.
Prior to the last couple weeks I put coolant in and light would eventually go out. Do not see any leakage. Now I just notice that the radiator fan is not blowing, what could be the problem? Thanks for your help.