Question about 2005 Ford Focus

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My 2003 ford focus during driveing thermostat runs all way hot , fan not coming on..When it happens I turn heat all way up and goes temp goes back to normal.. Is there a part called a thermostat resistor?

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Hello, this sounds like a Radiator Fan Relay problem. There are several parts which make the fan work and one can certainly be a resistor. There are two Temperature switches for the water, one for the dash gauge and the other for the Radiator fan.

When the water heats up enough, the Temperature sensor (using variable resistance), sends a signal to the Relay to trip. The magnetic in the Relay will continue to work until the resistence is diminished by cooler temperatures at the sensor.

At this point, you do not know if the signal is going to the Relay or not. The Relay may be bad and doing nothing with the signal. If you have a continuity tester (Ohmmeter) you can bridge the connector on the Relay to see if the magnetic coil inside is burned out(Not making a connection).
I would just use an Ohmmeter, not Voltage because the fine wires in the Relay coil can burn up from Voltage.

There is the possibility the fan motor itself is bad, but unless you can isolate the connector and see where 12 volts is going into the fan, do not short it out. But if you are confident you can test the fan with 12 Volts go ahead.

Would like to know how you made out with this.

Posted on Oct 09, 2010


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