my heater has stopped working in my ford ka i have changed the therm and still not working its still blowing cold air ... a friend of mine said she would check the matrix but we dont know how to get the dash off ???
Fiestas are fitted with a heater control valve - it would'nt surprise me if they are fittedto the Ka also - not expensive and easy enough to replace.
Most likely that it is faulty if fitted.