Tuscan fans

[jvr]

Out in the car today all hunky dory.On the way back got stuck in traffic,this gave the fans their first oppotunity to come on,however once on they never really turned off.All i could hear was a lot of faint clicking in the dash pod as the fans were constantly turning off/on off/on very quickly at low temps.Is it just the fan sensor playing up in which i can change or is it something else.
Any thoughts apprieciated
paul