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Old 05-19-2018, 07:12 PM
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*rayman* *rayman* is offline
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Default PWM Controllers or Relays and circuit breakers

I've been looking for a more robust solution for my thermo fans wiring.

I currently have 2 x OEM ford fans in a shroud mounted up to a large alloy Desert cooler radiator. This radiator is cross flow, and quite a thick core. It definitely has the cooling capacity to keep the big block cool enough even through harsh summer in Australia. The fans are quite high CFM, supposedly about 3800. They pull heaps of air when they are working on high speed. They are a 2 speed fan, similar to the Lincoln fans a lot of you U.S guys resort to. The fans are currently wired on a relay each, with an inline fuse on each fan, operated by a manual ON/OFF switch. I've been melting fuses at 30amp, and have temporarily put 40amp fuses in. These fans are running on the high speed mode, and are pulling i believe right on about 30 amps. It would be nice to soft start them, or even utilise the two speed mode they are capable of, and only run them when necessary.

I bought a Derale 16749 fan controller, but have realised the 25amp continuous rating is not going to cut it. I planned to control 1 fan, with the option to switch the second fan on manually if required.

I recently missed out on a SPAL PWM-3 fan controller.

I've looked at the other various PWM fan controllers, but the reviews of some of these controllers really don't inspire me on their quality.

I came across these TRAC breakers, and thought that i might resort to manually operated with these breakers mounted up near the fans to have more idea of whats going on. Anyone used them and have any feedback?



Anybody used this guys stuff?
68 BB SS Camaro - building it in Australia, where everything costs twice as much as it costs in the U.S.

Fuel prices suck!

Last edited by *rayman*; 05-19-2018 at 07:33 PM.
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Old 05-20-2018, 08:42 PM
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GregWeld GregWeld is offline
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So I don't have all the answers --- but would say this --- the START load on one of those fans on HIGH SPEED would certainly blow your 30 amp fuses....

I think your fuse size is not a big deal - but rather - either doing a soft start circuit ----- or starting on LOW speed and ramping to high...

Now --- the difference in PWM and "Two speed" to me begs a question for controlling.....

PWM is a variable speed controller

two speeds is two speeds

How were the two speeds controlled in the donor? Voltage?

I would think --- that the motors are just simply motors..... and could be controlled using PWM or just simple on/off switch or on/off/hi/lo. For hi/lo you just need to know the low V operation and the high V operation voltage requirement.

Since you now have a manual control ----- have you tried putting a variable potentiometer in the circuit and starting the fan at a lower speed??
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Old 05-20-2018, 08:56 PM
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GregWeld GregWeld is offline
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Forgot my #1 question!!!

So if everything works great with the 40A fuse.......

then you want to switch them automatically vs the manual you now have??

Or you want to run them with PWM??

Or you want to run them with two speeds??
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Old 06-07-2018, 10:09 PM
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Those Trac breakers look interesting. I have never seen them before. I like the auto reset feature. I would think that would be good for a fuel pump circuit.
Steve Hayes
"Dust Off"
68 Camaro
Speed has never killed anyone. Suddenly becoming stationary, that's what gets you!
"Jeremy Clarkson"
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Old 06-09-2018, 09:13 AM
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ProTouring442 ProTouring442 is offline
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What about this one?

The controller monitors your engine temperature via the radiator, therefore providing the most accurate reading for your cooling system. Using Soft Start Technology, fans ramp up slowly which eliminates harmful AMP spikes. The unit will continuously monitor your engine's temperature and operate the fans at the optimum fan rate as needed between 1 to 100%. The net result; the electric fans often only run between 40-60% to keep your engine cool. Additional benefits include, reduced fan speeds which means reduced fan noise, which tends to compete with that sweet sound of your engine!

This multi-fan controller has a built-in A/C Over-ride circuit and is designed to control as many 12 volt brushed electric fans as desired, up to 65 Amps combined.

Check out my blog and the latest installment of my current project "In the Company of Devils" at: www.WilliamKElliott.com
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