I went to my car the other day to find a flat battery. I called the AA who said the battery was fine and it's possible the radiator cooling fan isn't cutting out when the engine is switched off as this is a common fault. I've just tested it and the fan does run on until the battery is flat. Is this a common problem? Has anybody replaced one before or know where they are located? And how much did the part cost? Thanks for any help given.