I have a 1998 Ford Fiesta 1.4. Over the past couple of years the fan settings 1, 2 and 3 for the heater have stopped working (setting 4 always works) when the weather gets really cold. I thought it might be due to the resistors blowing as suggested in other posts on this topic. However, if the weather warms up again settings 1, 2 and 3 come back on?? Any ideas as to what could be wrong? Bit inconvenient in winter, but live-able with.