Another fire! I am just going to start the wiring over....

[ko67]

I had another friendly little electical fire. Before, I lost a fuse in the flexalite E-fan circuit. I checked for faults and replaced it. Then, I lost another fuse, this time to a small fire, (see prior post). I replaced the fuse holder and the wire with a higher rated fuse. Today, I noticed that my E-fan did not come on even though the temp was in the range it was set for. I opened the hood and heard a snapping, bacon frying kind of noise coming from the fan controller and a symphony of buzzing and smoke from the motor. I pulled the wiring loose and it was very hot. I dont know if the PC board in the controller failed and fried the motor, or if the motor failed and fried the controller, or if some wiring issue fried them both. I could spend the time to figure out what caused the issues, but I am not that patient. The PO put all of this in, and the wiring seemed sloppy. I ordered a new fan and controller and I am going to rewire this all the way back to the source, relays and all. I know I can either wire it to a constant 12v source so that it will cool the radiator to the set point after the key is off. I can also connect it to an ignition switched 12v so that it only runs when the thermostat in the controller hits the set point with the key on. The instructions do not seem to make a recommendation one way or another. Which way should I go, ignition switched or non-switched? I know that I will wire it to he a/c compressor relay so that the fan activate regardless of coolant temp unless someone thinks that this is a bad idea for some reason.

I will post pics of the install once I finish. I hate electical fires, even small ones.

 

[AzPete]

Run it thru the switch. As johnpro mentioned in a post somewhere, he killed the Optima battery in the '66 by having it wired hot. You really do not get any good cooling since the water is not moving thru the engine once you shut off the key.

Also, any time a fuse blows, there is a reason....never install heavier wire or fuses unless all has been tested and determined top be to weak to begin with.

A/C hook up is good too.

 

[ko67]

Also, any time a fuse blows, there is a reason....never install heavier wire or fuses unless all has been tested and determined top be to weak to begin with.

I hear you, boss. I installed the higher amp fuse because the PO had a 20 amp fuse on a fan with about a 17 amp draw, and a higher draw on start up, but it was a mistake for me to just put a bandaid on the problem when it happened the second time. (by the way, Pete, I found those 1/4 trim upholstery pieces and I will get them out to you later in the week.

 

[ko67]

Does it matter where I tap the switched 12v? Is the amperage the same/sufficient wherever I tap it under the hood? Starter solenoid ok?

 

[Horseplay]

I hear you, boss. I installed the higher amp fuse because the PO had a 20 amp fuse on a fan with about a 17 amp draw, and a higher draw on start up, but it was a mistake for me to just put a bandaid on the problem when it happened the second time. (by the way, Pete, I found those 1/4 trim upholstery pieces and I will get them out to you later in the week.

You don't necessarily need a higher amp rated fuse. What this type of condition requires is a slower reacting fuse. Not all fuses of the same amp rating work the same way. You need a fuse that can withstand the initial higher draw of the motor start-up.

The farther your draw originates from the power source the higher the amp draw will be. This is why power tools and such tell you not run them on long extension cords. Thicker wire can help to reduce this effect to some degree. The short distances under hood really don't make a difference in this case. Just make sure to run good, properly sized wire and make sure all the connections are clean and solid. Bad connections can also cause higher draw.

 

[daveSanborn]

If you're not using your electric choke wire, it's a great 12v switched source. Additionally I believe it's the red/blue wire running to the starter solenoid that's a good 12v switched source.

I wouldn't run it to a constant hot. It makes no sense to do so unless you're going to manually turn on the fan with a toggle switch.

Yes, wiring so that the fan comes on with AC is SOP due to the load placed onto the engine from the AC clutch/compressor and the necessity to pull air through the AC condensor.

 

[Sluggo]

Electrical fires are usually the result of using under size wiring or loose connections. Butt connectors, scotch locks and t-taps all suck. Solder all you joints, especially high amperage circuits.

Your 12 volt switched circuit should only be used on the switch side of the relay. The source for the fan motor (through the relay) should be the battery.

Not sure how the controller works but I would assume it switches on the power to drive the fan.

I would wire the output from the controller to the relay's + terminal on the switch side, and ground the other side of the switch. Run the power to the fan from the battery through a 30 amp fuse on 10gauge wire to the relay, out of the relay to the fan.

That way the fan is being driven by the battery via the relay. The switch side is isolated from the high amperage side which would also protect the controller.

 

[ko67]

Thanks Randy. That is how I will do it.