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Idk anything about any of the previously mentioned fan controllers, but here is what I can think of...

A. Install a higher amperage alternator and hope it handles the additional load/surge of the two fans coming on at the same time.

B. Use one temperature switch to activate one fan through a relay. Then add a manual switch to turn on the other fan, again through a relay, when you feel necessary.

C. Use two temperature switches. One to turn on one fan at 200F and the other at 205/210F.

D. Use one temperature switch to turn on both fans but use a timer circuit to turn on the second fan 20-30 seconds after the first.
It’s a bit more complicated but any electronics enthusiast can figure it out. Durability however, is more questionable. Again, use relays.
 

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Thanks for the reply. I guess I'm a bit frustrated and tired of trying new triggers and relays, etc. I don't wish to upgrade to a higher amp alternator. 130amp alt to run a set of fans that draw 25 amps running must be ample. Anyway, it's where I draw the line. I may try to change the thermostat and use a different temp thermo bmw switch with the volvo two speed controller, and see how that does. Or, I may just chuck it all and go with a nice soft start autocoolguy controller. I noticed on his site that he has an interesting temp probe that sits on the outside of the lower radiator hose attachment fitting. Interesting.

Anyways, thanks
 

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Hey guys. First time post here. I've been having the same issue you're discussing. I run a 2,000 Contour/Mystique dual fan. I trigger with a thermo switch in the top radiator hose, and that activates two relays, one for each fan. When I got the fan setup I removed the oe low speed resistor. I had assumed that the power draw with or without the resistor was the same. When the fans start the msd ignition sputters for a few seconds and the idle drops.

I run a hp ford 300, big cam, ported head, over-size valves, headers, Holley, etc.

There was some great info in the thread, but it left me with a couple of questions that I would very much appreciate if someone could answer:

1. Would using the Volvo relay/control pack stop the power surge, sputter issue?

2. If I wanted to start one fan later than the other, does anyone know how I would do that? Thank you very much.
I have been looking at this fan controller. It turns on one fan first and then the second fan comes on 10 seconds later. You can buy it through summit for $66. Seems like a well built product at a good price with control of the temperature that the fans turn off and on. Plus having one fan start before the other reduces the power spike seen when dual contour fans start up.

https://daviescraig.com.au/product/digital-thermatic-fan-switch-12v-24v-0444
 

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That setup seems like it's for actual dual speed fans. While the contour fans were dual speed in a sense they are not wired like a dual speed fan with two input wires and a ground. They only have one input and a ground. They were wired by two feeds one that went through a resistor on one that was full 12 volts. Both fed into the single input on the fan. I think you could make it work on a contour fan if you used the OEM resistor which @crackedblock states he doesn't have.
 

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Volvo fan relays are available on ebay for less than $20. You can combine it with a BMW 2 temperature switch.

https://www.fordmuscleforums.com/falcon-pages/544417-radiator-explorer-5-0-taurus-fan-volvo-relay-bmw-switch.html
That is true. I have two of the V. relay packs. I have tried them. The problem, however, is that the Volvo pack is made for a two speed fan. It is not soft start, so it does not prevent the spike on start up.

You guys have posted links to some very inexpensive controllers. They are so inexpensive that they worry me about durability and longevity. Did I miss any mention of warranty? My bad if I did. I simply could not install an unknown controller like those and feel good and confident about it lasting. But thanks for the links and the looks see.

I called to autocoolguy, since he is up the road from me. He warranties all his products for a full year. Although my Contour set-up spikes way up there, he recommends using his 55 unit. It is fused at 60amps. My fans draw together just under 30 amps, and since his unit is soft start, I will not get the huge spike. I'm considering using this system.

On a side note: I have noticed that since installing my efan system, I have to change my battery every two years like clockwork, or I pay the price of the system shutting down. My last battery was warrantied for 3.5 years, and died after two years two months. Converting back to a conventional fan would save a lot of trouble and expense. It may not be as cool, but I guess I would have saved about $1,000 and untold hours of work had I stayed with the oem fan with zero fuses, contacts, relays, over-sized alternator, thermo switches, etc.
 
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