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.

 

This will indeed be the resistor pack. When it's warm the broken connections expand as they are metal, which makes them work.

 

Turned out it was a small amount of corrosion on one of the connections to the resistor pack. Cleaned it up a bit, plugged the pack back on and now working fine. Thanks for the help though.