Why won't the heater fan work on a 1992-3 Land Rover Discovery. It occasionally works when the slide lever is waggled. It started by cutting out on the No 1 setting and progressed upwards over time.?

There is a resistor in the motor that controls the different speeds. If it works on full but not on the lower settings the resistor is burnt out.(very common)

If the fan isn't working at all it may be the brushes on the motor. Mine were sticking in the slider but not worn out, and tweaking the spring that presses them on to the commutator fixed the problem (intermittent running or not working at all)

This is a beast of a job as it entails removing the entire fascia/dashboard to get access to the fan unit. It is a full days task so don't rush into it lightly!

Pedro-C