It is supposed to operate that way. So if there is no signal being received by ecu then turn on fans as a safety. The fans shouldnt run all the time.
If your idling and the temp reaches the top dot and the fans dont come on then you could have a problem. First thing is to take it out and have a look. My old pintara, the fans were coming on when the car was too hot, coolant sensor was dirty/corroded, cleaned it with some emery paper and it was as good as new.
Do that first, and if still no joy then replace.