Help someone!!!!
 

Hello there, i desperatley need someone's help. I recently just bought a cooper S. But i'm having some problems.
well this is what happened.. On the first night I got it. I took it home, messing about with it you know how it is when you get a new car. And the temperature hand shot up. Bonnet as lifted and yes there was water shooting out of the water partl. I was told the head gasket was away in it. So I then ANGRILY rang the owner I got it off, and asked him. He said, anytime the car is sitting ticking over there's a little switch to the left of the steering wheel which controls the supercharger (this device I did not see) and anytime the car is sitting ticking over the switch must be turned on as the supercharger makes the temperature hand go up. and that I always do. But tonight I was driving it and the hand rose up, I then stopped it. Turned on the switch and it went back down to normal again.. drove the car and it then did the same thing again. Stopped put switch on etc.. hand went back down. Now I had to keep stopping the car the whole way home. I just stopped and got a lift. :( :( what is wrong?

There is no "factory" switch that you describe it sounds to me that the ex owner "rigged" up a switch to turn the electric fans on instead of fixing them correctly to turn on automatically