Ron Francis fan wiring question

[UpstateCobraGuy]

Guys,

Trying to get my fan to run through the FFR RF harness, basic carb 302 build. I’ve had the fan running off a “hot” off the battery (fused) to a thermal switch. Everything turned on fine, but the fan would not shut down when the switch was turned off. So, I changed the feed as recommended below…

“The standard Ron Francis wiring for the cooling fan is: Dk Blue Cooling fan +12V wire in the front harness to the positive terminal of the cooling fan. Negative (or ground) of the cooling fan to chassis ground. The front harness includes a black ground wire. The green thermo wire goes to your sensor. When the sensor reaches its rated temperature, it closes and the green wire goes to ground. This causes the cooling fan relay in the Ron Francis harness to energize (close) and +12V goes to the Dk Blue Cooling fan wire and the fan should run.”

I should be able to trick it by grounding the feed to thermal switch. Unfortunately, nothing. Checked fuse. All good.

What’s my next move?

Thanks in advance…

Pat

[marshc56]

Have you checked the relay?

[michael everson]

If you are trying to get the fan to shut off with the key, you need to move the positive wire feeding the trigger side of the relay to a circuit that is shut off with the key. Radio power wire could be used. or wiper / heater if your not using them.
Mike

[UpstateCobraGuy]

Yes, swap them between horn and fan. Fan no nothing, horn very loud…

[UpstateCobraGuy]

If you are trying to get the fan to shut off with the key, you need to move the positive wire feeding the trigger side of the relay to a circuit that is shut off with the key. Radio power wire could be used. or wiper / heater if your not using them.
Mike

Trying to use the fan relay. Grounding out the green “fan thermal sw” wire isn’t doing the trick to turn the fan on or off.

[phileas_fogg]

Forgive me for stepping all over Mike, but what I think he's saying is that the RF harness is wired such that the fan runs until the sensor comes down to the threshold temperature. In order to have the fan shut off when you turn off the car, you need to move the Dk Blue Cooling wire off the Battery circuit to the IGN (or ACC) circuit. The thermo sensor is in the ground leg; as long as the sensor is above threshold temperature, it completes the ground leg of the fan power circuit.



John

[michael everson]

If grounding the green wire doesn't work, check the following
Fan fuse
Fan relay ( swap with horn to check)
Fan plug
If all this checks out you might have a bad fan.
Do you have power at the #86 terminal on the relay?
Mike

[UpstateCobraGuy]

If grounding the green wire doesn't work, check the following
Fan fuse
Fan relay ( swap with horn to check)
Fan plug
If all this checks out you might have a bad fan.
Do you have power at the #86 terminal on the relay?
Mike

Thanks Mike!

I’m probably my own worst enemy and didn’t hook up power back to the relay. The last thing I want to do is to remove my dash. (Long story) I’m going to hook up another relay and call it a day.

Thanks for the help…

Pat

[brewha]

It’s been awhile since I wired but if I recall it right, there are 2 green thermo wires. If either are grounded, it will complete the circuit and run the fan. One wire goes either to the thermo ground switch or temp reader on a fuel injection system. The second wire is optional. I used mine to go to a switch to override the fan if I choose to.

Also there should be 2 themo sensors on the motor. On is for the gauge which could always be grounded but sending a different resistance to the gauge and the other sensor is just open or closed as it senses high heat. Don’t use the gauge sensor for the fan. Good luck….

[UpstateCobraGuy]

I just got back from a nice 20 mile ride. I ended up wiring in a new relay and it functions perfectly and shuts down when I turn off the key. Which is key, so my battery will start the car when I return. 😉

Thanks again,

Par

[marshc56]

Glad to see it works "as advertised". I'm working on my wiring now. I selected a relay "pack" to control the lights. Working on 'splicing' it into the RF harness. I'm adding in a fan override switch for redundancy.

Marsh