ac fan won't turn off

[mx5ash]

Hi guys,
My car had a flat battery recently so today i recharged the battery and put it back in. As soon as the battery is attached the ac fan (one on the left looking from the front) comes on and stays on even with the key out. Must be why the battery went dead in the first place.
I have pulled the plug on it but can anyone shed any light as to why its doing this.
Not sure when it started but pretty sure i wasn't doing it last time i was doing things to the car (last weekend)
What could have happened to make it do this without anyone being near it?

[mx5ash]

Its the relay, seems a bit wet and when pulled no more problem.