The two auxilliary electric fans on my recently acquired 1997 Discovery V8 weren't working either until I replaced the motors (with Nippon Denso parts for the equivalent of a little less the USD100), didn't notice because the main mechanical fan was doing it's job (temperature never exceeded mid-point). Nevertheless, replaced them for insurance (automatically turn on with the air conditioner or presumably if the engine temperature exceeded a certain level). Now the temperature gauge seems to hover a bit below mid-point most of the time. Would suggest you do the same if you haven't already. They say aluminum engine blocks, heads & gaskets, as Discovery 1's have, don't do too well with heat build-up.