Fan Fail Jumpers burned

[Bitsyncmaster]

Got this photo today from my friend. I'm guessing the fuse sockets failed. He said there was flames from the rubber burning. I will send him my fan fail unit but would like to check his fan currents.

That gave me an idea I may work into the fan fail unit. What I could do is if one fuse is missing (or blown), I could flash the fan fail with the current being drawn by the working fan. So 10 flashes, 3 second no flash and repeat would be 10 amps.

[hmcelraft]

I have seen that condition on several cars. I have always felt like frequent fan cycles overheat the circuit. Each fan can draw nearly 20 amps to start. If the AC system is low on gas and the fans are constantly cycling with some frequency - that is a lot of heat. A fan delay and fan sequencer circuit is useful. I have also found that a separate relay and separate HD 15amp circuit breaker for each fan is nearly bullet-proof. I also run the fans all of the time the AC is on with a delay sequencer for shut-down when they turn off. I sourced the fan relay power directly from the battery post. That seemed to take some heat out of the circuit and stress off the rest of the wiring too.

[Bitsyncmaster]

A fuse that is running near it rated current will generate a lot of heat. Maybe the rubber on those fuse holders is just insulating the fuse to much from dissipating that heat.

Maybe a good idea is to cut that rubber down so most of the fuse is exposed.

[Bitsyncmaster]

I'm still thinking about improving my software to give owners more warning of a marginal condition in the cooling fan circuit.

Now my unit will warn you if one or both fans stop working. It uses a current reading of 3 amps to call a fan not working if below 3 amps. That will show you if a fuse blows or a wire disconnects.

I also compare the fan currents and warn the user if one fan is drawing more power than the other fan. That would will show you one fan is going bad.

I could add if one fan is drawing more than 15 amps to flash the fan fail light. Now how common is a 15 amp draw? Or should it be set for 16, 17, 18, 19, or 20 amps?

Any fuse or circuit breaker running near it's rated current will run very hot. Even running at half the rated current the fuse will run warm. A 20 amp fuse running 20 amps may take one hour or more to blow the fuse. Now that same fuse running 25 amps should blow very quickly.