Cars dead. Won't start. Fan runs when it would start.

[baz_rochdale]

As the title says. I've just gone out to start the car and just a load of clicks. But I noticed that my cooling fan has been running as soon as I start it up when it's cold. Will that kill the battery?? And what causes that to happen. Any help now would be fantastic as I'm only off work tomorrow so need to fix it then.

Cheers!!!

[mozzer99]

Normally a load of rapid clicks is simply the battery is very low and can't turn the starter, just the solenoid goes back and forth.
If the aircon is on, one of the fans is on all the time.