help..................please.

working on an early spf. car built in 1996. not sure what number. owner thinks between 750 and 1000. anyway trying to make fans work by switch and thermostat. now there is a switch on the dash. has two black with yellow stripe wires. but nothing happens when switched.

checked for fuses and there are only 4. all are good. two 20 amps and two 15 amps. so, can anyone tell me what that switch with those black & yellow wires is supposed to do? on my car spo2669 those same colored wires are for the fuel gauge. so i am kinda lost can anyone please help?
