[jhv48]

If the fan coming on doesn't seem to effect the temperature, then your thermostat is defective.

When the water is hot, touch the radiator hoses. Are they good and hot too? If not, then the thermostat is not opening. Or, if warm, but not hot, then the thermostat has one or more 1/8 inch holes drilled in it that are letting some water flow though not enough to adequately cool the engine.

Do the air purge thing first. Then, if no change, replace the thermostat.