Radiator Fans and water temp

[shlim8]

I'm posting this here on behalf of a friend who has a 2000 996 C4, I'm assuming that the cooling system will be similar to a 986, hence... posting here.

Suddendly over the last one month, my friends 996's radiator fans has been coming on (low) at 100 degrees C and high at 103 degrees C. Hence, the water temp (at gauge) is alternating between 100 degrees C and slightly below it. Used to be about 90 or so.

So far, since then, he has changed the water pump (original), LN low temp thermostat, flushed the coolant but the characteristic is still unchanged (strange..). He has also taken the bumper off and cleaned the radiators (bagful of leaves, stones etc).

I'd asked him to look at the aircon diagnostic and the only possible clue is that his 1C (oil temp) reading is very low - can be 50 degree C when warmed up and even had a reading of zero. The 6C reading is similar to the water temp gauge - 100.

Is the DME "smart" enough to delay the radiator fan operation as it thinks the oil is not warmed up yet ??? That might explain the problem ?