Auxiliary fan on from start up.

This has probably come up before but as I am new to the site I thought I would ask anyway I have just done a complete oil and filter change as well as the coolant. Before I did this I had issues with the heating and my auxiliary fan running from the moment I started here. Since the oil and coolant change she feels much smoother but the auxiliary fan is still always on. Is there a way to stop it with out buying a hawkeye, permanently removing a fuse or putting her into land rover.

If anyone can help I would really appreciate it.

Cheers

This is the aircon fan. If it comes on all the time the engine has overheated at some time and the control unit needs to be reset using nanocom etc.