on the fiesta there is a problem with one of the GREEN relays.... its melts then stops working...

this affects the revearsing light and the FAN.... if you don't have an over cooled engine this leads to engine death! The relays can be got on EBAY £3 or your local scrapper for less.

the other thing you can do is pressure test your cooling system. This will tell you if you have a leak and also of it gets over pressured then somthing is running V hot in the engine