How can I fix overcooling on my mondeo 2 ltr automatic?

you can test the electricals by plugging in a spare sensor dipped in boiling water (at 90 degrees it should read half way on the gauge) just turn on ignition don't start the engine. It may be possible to use a carefully selected resistor/resistors .Try 96 ohms in series with 39 ohms (135 ohms) assuming it is a PT100 type sensor this will simulate 90 degrees Celcius.
If its the water coolant thermotat then check that you can undo its housing easily before you get a replacement stat. motor factors have stats for under £12, ford may charge you £30 but if the housing cant be separated a new housing complete with thermostat whether you need it or not is £40 from ford cant just get the thermostat housing!
It may be something else like your ECU software?

Emin Nesheli
October 2008

I have the same problem on a '98 1.8 LX petrol. I think the thermostat's stuck open and will need to replace it.

Joe
December 2004