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Old 04-19-2014, 09:48 PM
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Electric fans not going on

Hello
I just installed electric fans in my 55. The radiator temp sensor is supposed to come on at 195deg. Because the fans aren't coming on I replaced the temp sensor and the fans still won't come on. When I ground the temp sensor the fans come on so I know they are working. I'm not sure what else to do except change the fan relay. If anyone knows what the problem is I would appreciate the help
Regards
Doug

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Last edited by 40forddgc; 04-19-2014 at 09:52 PM. Reason: Typo
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Old 04-20-2014, 06:22 AM
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If the fan comes on when you ground the sensor lead, then the system is operating correctly. Either your sensor is not grounded to the radiator or the radiator is not grounded to the car. Radiators are usually covered in thick black paint and they're not always grounded. clean the paint off around a mounting hole and see if that works.
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Old 04-20-2014, 06:55 AM
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no fans

if by grounding the temp sensor u engage the relay and turn on fans... then the sensor is the problem not the relay.. maybe too much teflon tape on the threads of sensor, bad sensor ??? is the temp getting to 195 ??
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Old 04-20-2014, 07:45 AM
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When I see a post like this there are so many questions that pop into my head,like how is the system wired? does it use a relay, a fan controller,or is it just wired some other way? what kind of electric fan.what size,1 or 2 speed? is it wired to a binary or trinary ac pressure switch? what kind of temp sensor?if for a guage will that work with just resistance? is the engine grounded to the frame,body,back to the battery,good call on the teflon tape not allowing the sensor to ground,more details please!!!!
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Old 04-20-2014, 12:42 PM
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test

Make sure you have switching sensor and not gauge sensor.
Also, the sensor could be tested in a pan of water, using an ohmmeter and a thermometer.
When the water temp. is less than the sensor rating the ohmmeter will read infinity (no resistance). When it reaches the rated temperature, the sensor will switch and the ohmmeter will read continuity (completed circuit).
If ohmmmeter reads a resistance change as the temperature increases, you have the wrong type of sensor.
This ohmmeter test could be done with the sensor in the engine. Disconnect the wire to the relay and connect the ohmmeter to the sensor and ground.

vicrod
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Old 04-20-2014, 01:17 PM
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That's what I love about an engine-driven fan.
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Old 04-20-2014, 03:40 PM
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If you bought this as a kit, make sure to follow the grounding instructions carefully. Not a fan of the attach to radiator type sensors, much better IMO, to place the sensor in the engine block using one of the head mounting location (SBC)
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Old 04-26-2014, 06:18 PM
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Problem solved on fans not going on

Guess what? It was the temp sensor. Thanks to all for your help
Doug
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Old 04-26-2014, 08:48 PM
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just a follow up

Was it the wrong sensor or a bad sensor?

vicrod
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