There are two electrical fans behind the radiator and one runs continuosly when the engine is running. the other switches on when the a/c is switched on. but sometimes the second fan doesnt switch on and the engine temp climbs up to the middle mark. The technician told me its regulated by a thermostat switch or maybe the fan needs to be replaced. How do i rewire/configure these two fans to be running instead of just one? I dont want to use the a/c as a 'switch'