Electric fan question

If you don't have a high current alternator, you can forget about using the fan. The stock 65 amp alternator isn't big enough to run the fan and the rest of the car.

Switching a fan on and off manually is a bad idea. Too many guys have been distracted (hot girl kissing on their neck, too much to drink, dog tired and not thinking clearly) and cooked things because they forgot to flip the switch. An equal number have forgotten to turn the switch off for the same reasons and run down their battery.

The best fan controller available today is a DC Control unit. www.dccontrol.com. Cost is about $110. Be prepared to wait 4 weeks or more to receive your controller once you have sent in your payment. The controllers are custom made in small lots and lead times can stretch out.

Next best is a SPAL controller - $70-$90 See http://www.spalusa.com/fans/automated/accessories/fanpwm.html. Ebay will have the controllers for the $70: do a google search and see what you find.

At the bottom are the Hayden or Imperial controllers available through Advance Discount Auto Parts and AutoZone. The non adjustable one is about $30 ( Hayden 226206) and the adjustable one is about $60 (Hayden 226204). I recommend you do a Google search on Hayden and the part number for more info.

Do not use a simple on/off switch without using a relay. The current load can burn up the typical cheap automotive switch very quickly. The fan draws 30+amps and you need to use #10 wire on the fan power and ground wiring.

If you are good with electrical stuff (90% of the people here aren't), build your own controller. The numbers on the diagram (#86, #87, etc) refer to the numbers on the bottom of a typical automotive relay.



Note that the temp sensor in the diagram isn’t really suited for the job. You’ll have to do a Google search and find your own.

This version of the fan controller will continue to run the fan after the ignition switch is turned off, just like most new cars.
To allow the ignition switch to control the fan so that it does not run when the ignition is off, connect the relay contact #86 to the red/green wire on the ignition coil or to the red/yellow wire on the coolant level sensor.

If you are an experienced electronics tech or electrical engineer, email me and I will send you the prototype drawings of a fan controller that is probably as good as the DC Control unit. It is a build it, troubleshoot it yourself item. I will not build or troubleshoot units, so it is not suitable for anyone who isn't really good with electronics.

Alternate placement for a temp gauge sender or temp switch/temp sensor for an electric fan. Use the heater feed that comes off the intake manifold. Cut the rubber hose that connects the manifold water feed to the heater and splice in a tee adapter for the temp gauge sender. Be sure to use the same water feed line as the ECT sensor. That way you will get the most accurate temp readings.

Tee adapter info:
Make a pilgrimage to your local hardware or home supply center and get some copper pipe and a tee that fits the temp gauge sender. Solder two pieces of copper pipe onto a copper pipe tee with threads in the tee part. Find the correct brass fitting to match the temp sender threads to the tee fitting.

Electric fan = 3G alternator if you want long life & reliability from your car.
The electric fan saves some HP. The stock fan's parasitic drag runs from 7-12 HP depending on who you talk to. The electric fan uses about 1/2 HP of power from the electrical system.

Figure this:
Ignition system & computer = 12 amps
Fuel pump = 12 amps
Exterior lights = 15 amps
Fan (heater or A/C) = 15 amps (can run between 5-25 amps depending on setting)
Radio & instruments = 10 amps
Wipers = 10 amps

That's grand total of 74 amps from a 65 amp alternator. Talk about overdrawn at the bank!

The electric fan draws 25-30 amps constant current with a 75-100 amp surge at start up. Now you see why a high output alternator is needed.

Stangnet 3G install sticky see http://forums.stangnet.com/showthread.php?t=646825

Brandon11010 said:

....no wthe instructions say i can run the smaller red wire thats i have attached to the solonoid to a switched source, so the fan shuts off when i turn the key off.....

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If you have not done it, this is something you need to do even if you have a 3G.

Set it up so the relay coil is only energized with the key on. Common sources for power for the COIL of the relay (terminal 85 or 86) are the low coolant sensor or VPWR.

Then follow Jrichker's wise advice when you get a chance. You'll be glad you did.

Good luck.

I agree with jrichker about the DC controller... I got mine awhile back and it works like a charm. Simple design, easy to install and has run my fan flawlessly since it was installed. Great product...

Brandon11010 said:

Would just getting something like a 2G 100amp alternator from summit solve my problem?

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Nah, get the 3g, it puts out more amps and on top of that it's a safer design. The spade connector on the 2g can catch on fire with the 65 amp alternator, I wouldnt want to feed a 100 amps through that thing.

Go to a local you-pull-it yard and look around for a 94+ mustang. They have 3Gs and grab one from there. The install is pretty straight-forward and there is a mountain of information on here of how to do it. I think there is a sticky somewhere? Either way, the alternator won't cost ya too much, and you will not have charging problems after the install, I promise.