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Old 08-16-2006, 11:18 PM
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Radiator Fan Switch--which way to go?

I installed a temp sensor on the water outlet that triggers the radiator fan at a certain temperature. The unit has not been very dependable and I am told these units have their problems. Has anyone used any particular sensor that gives dependable performance? I would like something that switches the fan on at around 185-195 degrees and does not use a radiator probe, if I can avoid it. There are a lot on the market, just not sure which one works best.

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Old 08-17-2006, 02:21 PM
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Painless Wiring makes a kit that includes the temp. sensor, a relay and a circuit breaker.

The temp. sensors are available in (2) temperature ranges.
Turn on at 200* and off at 185* or
Turn on at 185* and off at 170*.

A relay is required to handle the high current required for the fan motor.

Make sure the coolant thermostat rating is LOWER than the OFF rating the temp. sensor. A 180* thermostat for the 185* sensor or a 160* thermostat for the 170* sensor.

The temp. sensor should be installed in the cylinder head or the intake manifold to work correctly.

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Old 08-17-2006, 05:17 PM
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If you installed a relay.you should be able to splice into the wire going to the thermo switch to one side of a on/off switch,and the other side of the switch to ground.When switch is grounded the relay will close sending voltage to the fan motor.Im sure that Doc vette has a schematic showing this circuit.
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Old 08-17-2006, 06:58 PM
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older pontiac 6000's used a relay that supplied power to the fan at all times and then used the coolant sensor for ground,that way the fan could work when needed and was easy to figure out and test.
the stock sensor didn't come in until about 230 degrees though so another colder sensor might be in order.
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Old 08-17-2006, 07:34 PM
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I have used the following (avail from Summit Racing) for several years and it has been flawless. Completely adjustable. Contains everything you need to hook up your fan including the relay, pre-wired temp probe (intake mainfold), and inline fuse. Also has a lead from the relay unit which will let you override the thermostat to turn on your fan - hook it up either to a switch on the dash or your 12v pos lead on your a/c clutch to force the fan on when the a/c goes on.

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Old 08-17-2006, 09:46 PM
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fan controller

I like the CenTech fan controller because it has an under-dash rheostat to "fine tune" it. Bill
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