Mark-

If you have AC your fan should come on as soon as you switch on the AC. If
it does not come on, check the radiator fan resistor behind the driver's
side headlight (you have to remove the headlight to get to the resistor).
That was the culprit on my fan. Didn't know I had the problem until my AC
hoses ruptured from the pressure.
I have more details on troubleshooting this problem that other listmembers
sent me  if you need more help.

MTB