im having problems with my fan on a renault scenic?

my fan comes on all the time i know its not the thermostat as the temp gauge does not go above half way like it should and it comes on first thing in the morning when i start the car.it keeps on starting and stopping but its on when the car is moving, it wasnt like this in the winter, i know the fan cools the water but it shouldnt come on when the car is moving and it shouldnt come on in the morning

dave
May 2009