[Barnsnake]

If your engine is not reaching operating temperature, the problem is with the thermostat.

Here's the way I prefer to wire the fan circuit:

The fan is controlled by a relay that connects the fan + to the battery +. The other side of the fan is grounded. The relay connector has two large wires, one goes to the battery via a heavy fuse, the other goes to the fan. Power the trigger side of the relay with switched power. The fan relay is triggered by grounding the wire that goes to the temperature switch (the switch goes to ground when it's specified temperature is reached). You can use a toggle switch on the dash to "bypass" the temperature switch and turn the fan on regardless of temperature. Wire one side of the switch into the circuit that goes to the temperature switch on the engine and wire the other side to ground.

With this system the fan runs only when the engine reaches the thermal switch temperature, or when the override switch is flipped. The fan stops when the key is turned off.