NYMESRLOKZ

So i am having a little issue with my 04 530I, i drive about 40 miles every morning from my house to work and 40 mile back home,I've noticed lately that my fan starts going crazy after driving it around an hour. I get to my shop in the morning with the fan on high i don't use the A/C i parked for about five minutes, i took another drive around 50 miles more i get there and the fan was not on, i drive back to my shop and now the high fan was back on. I don't get any warning lights, car is running great did complete maintenance including radiator flush. what could it be? can anyone help? thank you