Just turned very cold, I put the heater onto 'hot', this may be a coincidence but my temperature needle constantly goes above the midway point towards the red before the radiator cooling fan switches on! Then it turns off after 10-20 secs while the temperature remains around the midway to upper half point. The car never used to do this in the summer where the temperature stayed a third to a maximum of half way up, then the fan kicking in for a longer period to cool the engine. What do you guys think is the problem?