Dual Electric Fans

[W350Eddie]

Has anyone does this conversion from the clutch fan? I've basically put it in, they're derale dual electric fans part number 259-16027? http://www.summitracing.com/parts/DER-16027/ It comes with a thermostat, which I've put it and have it connected to one fan, the other fan has been disconnected. Can I run the second wire safely to the power of the AC compressor? That way when I'm running the AC the second fan kicks on. I'm just worried about over pulling from the AC compressor wire... Also, are there any better ideas? Should I just run both fans off the thermostat, or since there's a relay for each fan, i could even wire it to when the contactor closes on the first relay (hooked up to the thermostat) it powers the second relay... open to suggestions...

Thanks!

[CAJUN 93]

wire the trigger wire for the seconds fan's relay into the wire for the a/c clutch. i would also run an override thermostat to run the 2nd fan when the temp hits a certain point whether the a/c is on or not. you'll have to add a diode in the line from the compressor clutch and relay to keep the override circuit from back feeding and keeping the a/c running. not hard to do at all and should work just fine.

daryl

[CAJUN 93]

the biggest thing to remember with fans is small wires are your enemy. the trigger wires on the relays are no big deal as they dont really carry any amps, but the wires that actually carry the load for the fans should be as big as you can reasonably run. amp draw creates heat, heat creates melted wires which results in roadside cussing. other than that you should be fine.

daryl

[monoblock]

I have considered fitting a used 18" 2 speed electric fan .
Controlling the second fan(in your case) or the high speed(in mine) can be achieved in other ways than those already suggested. One is to use a higher temp thermostatic switch for the 2nd fan.The advantage is the redundancy -if the 1st fan fails ,at least the 2nd one will save you?
The other simple option is to have the 2nd fan(or high speed for me) controlled by a simple manual switch with a warning light.
What objectives were you trying for with the electric fans? I ask because it is an expensive mod. Had you considered an electrically controlled fan clutch(is there one for this truck?) like Dorman #622-003 from 2003-09 Dodge trucks.

[Gots_a_sol]

I'm using the ford taurus 2 speed fan in my truck. It came up a bit short with the auto trans but it does the job just fine now that I switched to the manual trans. Fit is pretty tight. I had to modify the stock brackets which stands the radiator up straighter.






Here is how I wired mine. It just uses relays and a temp switch (mine was from a Honda). The a/c side runs low speed and the temp switch turns it on high (uses 2 relays to provide enough amps without burning them up or needing an expensive single relay). When it switches on high, it removes power from the low speed circuit so it isn't trying to power both at the same time.

[monoblock]

There are several Taurus 2+speed fan wiring diagrams on the Internet if you search "Taurus fan wiring" .Some have more features than the helpful diagram above.Don't get muddled with the twin fan set-ups(Ford Contour).
Instead of relays,I looked at several more sophisticated controllers(Summit Racing) -Spal,Dakota,Flex-a-Lite and DCC .I decided to go with DCC despite the warnings about delays in shipping and rather spotty customer service. DCC is owned by a Brian Baskin who seems to be a very competent electronics entrepreneur. Like him ,my social skills are also best described as 'spotty' so he seemed a kindred spirit.His product gets excellent reviews and it has been available for many years-so is well proven and reliable.
The virtue of these sophisticated controls is the soft start and variable % of power. My alternator is stock and I have only one battery -they run a large hydraulic pump for the dump bed I fitted. I have to let the engine idle while dumping and if the weather is hot, the a/c is on +the big fan.I did not want to overburden the charging system while dumping.The DCC controller is not much more than buying 3 Bueller relays and the diode (required to stop the back-feed when the a/c is running in some configurations). I like wiring up my own circuits and have done this circuit before on an XKE with a Lincoln Mk V111 fan. I just wanted to try something different.
DCC's spartan website might alarm you but all you need is there but not one superfluous word!
http://www.dccontrol.com/selector.htm
If you are buying a Taurus/Lincoln fan ,be sure to know what exact vehicle & year it comes from.You need this info to get the correct 3 wire connector to the fan motor. The fans go for about $100 on EBay.The connectors are expensive($30+) unless you know the exact info to get a generic one- so try to buy a fan with the connector and as much harness as possible. Remember there is a very convenient plug for a temperature sender next to the thermostat.You just need a good quality Allen socket (9/16"?),PB Blaster and lots of patience to let it soak in.
Remember you must NOT power both the low and high speed circuits simultaneously.I mention this in case you decide to design your own circuit. 87 & 87A are your friends!
I hope this is helpful.