just my 2 cents -
dili maau epa direct ang aux fan kay dali ra hinuon ma wear out ang fan kay on naman all d time. the more delikado maguba ang aux fan along d way, ma overheat na hinuon, mas dako na problema. if efi na imo engine, in theory mas mo kalas pud ug gasolina na hinuon kay bugnaw man ang engine temp (aux fan always on) - as one poster already said.
so, depende sa design sa cooling system sa imo car, it could be the thermoswitch if it got one or, this is my hunch, wala maau pagka bleed imo cooling system, naa pa air pockets mao dili maau ang heat transfer going to the temp sensor mao dugay maka trigger sa aux fan. again, this may or may not apply to the specific design of your car. i dont drive a honda so in generality lang ni ako opinion.
does it turn on right away inig on sa AC? kay kung erratic pud then it could indeed be a faulty aux fan na.
hope that helps.