New here, went through past info on wiring an electric fan running into problems, any help is greatly appreciated,
Situation: wiring in a Perma-Cool 12" fan to OEM 74' Valiant, purchased through Summit Racing with recommended theromo switch wiring set also made by Summit. Wired following wire diagram to a T and got no activation.
Trouble shooting: tested fan off of battery, checked out fine. Bought new relay. Tested 30 amp fuse. Ran thermo wire to block temp sending unit which I know to work. Checked power source running from starter relay switch.
Conclusion: I know I am missing something easy and simple. Thank you all for reading and feed back.

Do you have links of what exact switch you bought?

I hope you've upgraded your alternator and wiring. Even a fan that draws modest current will give the stock electrical system a hard time.

Don't know exactly what you bought but the system should be triggered by the thermo switch giving the relay a ground, thus firing up the fan. The relay should have a hot from a keyed 12v source, and wait for the ground at the correct temp. The high current side of the relay should be attached to the battery, then to the fan, then to ground. Does the fan have a good ground?

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KAKAWWWWWWWWWWWWWWW!!!!

Electric Fan:
http://www.summitracing.com/parts/prm-19122/overview/
Thermostat Switch:
http://www.summitracing.com/parts/sum-890015

Upgraded alternator, the fan does have a good ground.

The original sending unit driving the dash gauge is a different beast, it won't do you any good here.

Remove the wire going to the sending unit and ground it. If the fan still doesn't go on then something's the matter between your fan/battery/relay wiring. Does the relay click ?

If the fan does go on then your issue is the switch. It may not be the switch itself... where is the switch located? The outside body of the switch (threaded portion) needs to be on a good ground. If you put it in the radiator, and the radiator doesn't have a good ground to the core support, you'll have to run a wire directly from rad to battery. Sometimes if you use sealing goop on the switch then it won't make good contact with it's surroundings. Check resistance with your multimeter between switch body and battery negative, should be very little.

I know this may sound absolutely ridiculous, but have you tried to reverse the polarity of the input wires to the fan?
I recently heard a story similar to yours, and the reason the fan would not start while driving, was that once the car was underway and the fan started turning from the wind speed, it turned out that the fan was electrically connected to run the opposite way, and that proved to be too much strain for the fan's motor! It also had too thin wires for the power supply, remember, some fans may draw up to 30 Amps during startup!

If you connect the relay to battery power, the fan will also be active after turning off the ignition, which will also reduce the possibility for fuel evaporation because of hot fuel lines/carburetor. You can add a time switch if you feel it is running too long.

Olaf

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Aspenized

Green Monster,

Can you short across the fan switch and get it to run? That is a god quick test to see if the switch is faulty or not...

You can follow my simple electrical diagram in the FAQ. Pretty basic!

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG