radiator fan not turn on

[slivia-junkie]

now if this has been posted i am sorry but my search didnt find anything

i have a s14 sr with a koyo rad and a stock electric fan with no shroud. my problem is that when the car gets hot the fan doesnt turn on. the fan works if i jump the relay so i thought the relay was bad, i replaced the relay and it still doesnt work. i then wired a perminent jump over the relay with a fuse and the radiator fan then worked for a day with constant on(key on fan on). now to day the fan is backto not working. i checked fuses still good but no fan. now the jump was over the radiator hi relay now i can still get the fan to turn on by jumping the rad lo relay. does any one have any ideas on whats going on and if i jumb the lo relay will that stop working to? i would rather have a constant on then a swich but will do whatever works
sorry for the novel but any help or ideas would be great, thx