[macx]

I just bought a fancy - and expensive - variable speed
Flex-A-Lite electric fan controller with soft start, etc,
to run a 3.8 Taurus fan. Thought I was all set.

When I opened the controller package, I find out it
will carry a max load of 30 amps, and I've read in one
place that the Taurus fan pulls about 33 amps on high.

Anybody know for sure?

I hope I didn't spend close to $100 for nothing!

[302 Z28]

If the original equipment fan draws 30 amps the wiring should be designed to handle that, and 33 amps will probably be OK as wiring size is generally derated.

Vince

[docvette]

Doc here,

33 amps is most likely "worst case , hard start" figure on that...you should be fine, however, use a fuse link on the fan, not a fuse..a fuse will open on a spike..where a link will hold up for a period of time under the same load conditions before opening..

Rotor locks are what you need to worry about..Anything that mechanically locks the fan blades..(like a plastic bag wrapped up in it..) The motor can draw multiples of rated current before disaster happens..again why a proper link is tantamount..

Doc

[slvrbllt]

I can tell you this. Make sure you have the plug-in off the taurus,if you use
regulare connectors you have to much resistance. Use relays as needed
to save the control and mainly use a breaker instead of a fuse. So if it trips when the breaker cools off the fan will run again

Them damn taurus fans are easy to mount on a lot of things, but when they get old they are some juice hogs. Feel the fan motor if it gets to hot to touch
trash it. Would be a good idea to hook up a LED on the dash so you know when it it running Almost lost a an engine once, the fan was running too hot and blew the fuse while the car was idling unattended, since then everything gets breakers.

[docvette]

Doc here,

If you use a link, it will hold up better than a fuse (re~settable or not) Because a link Requires "Heat time" to heat up and melt..and IS not susceptible to High current spikes..(like start up) where a fuse or breaker will let go...(leaving you Without Cooling)

A motor Must overcome physics To operate at startup..This equates to: it takes a healthy shot of current to get the fan to make revolution #1 from a dead stop..draw at this point is maximum,.(maximum Current required for maximum magnetic pull) until and as the rotor comes up to speed..The momentum of the rotor and (ergo, the fan) relieves the need for high current to keep it turning..so the draw level decreases as speed increases..

Anything that poses a restriction to the rotor will cause the windings to draw current exponentially in an attempt to overcome the restriction..this condition (when dead stopped at full power) is called rotor lock..When this occurs , it will heat everything..wires, fuses, windings etc , until it finds the weakest link and burns that open..(usually, and hopefully the fuse..)

On a Theoretical 1 second screen shot of a Theoretical fan circuit, your motor draw might look like this at start, or cycling in temp mode..:

35 amps.............27 amps...............18 amps..............8 amps <--draw
==============================================<-Equals 1s time
0 to 1 rpms.........500 rpms..............1500rpms............2500rpms <--speed

you can see where the most current is ..At startup, where a fuse may not be up to the task..if you need time to recline the draw..a link provides that .."heat instead of Spike time"

In a "Rotor lock" situation it may look like this: (plastic bag sucked up and stuck in the fan blades, seized bearings etc..)

35 amps..........50 amps..............70 amps...............90 amps <--Draw
==========================================<--Equals up to 10s
0 rpms............0 rpms................0 rpms.................0 rpms <--speed

Although, these are just Representative of what it MAY be doing, in order to give you a Visual aid... it aids in giving you an idea of what is going on..the actually math may differ a lot..in the real world....But HERE you would want the link to open, and after a short period of heating, (melt time) it will and render the circuit safe..

So you can see why it is helpful to allow time instead of spike to protect this type of circuit..

Your Controller SHOULD have a proper relay already inside of it to control the fan, But you should check to be sure, and if not, install one externally..If it is temperature controlled, it should have one.

Be sure the Wires are up to the task, I would recommend 10 gauge for the fan to controller (or relay) and 18 gauge for the controller power, ground and signals..and don't forget the controller will require a low current fuse too (if not already on the unit)

Everything you NEVER wanted to know about motor control 101...

Doc

[58Chev]

Originally Posted by macx

I just bought a fancy - and expensive - variable speed
Flex-A-Lite electric fan controller with soft start, etc,
to run a 3.8 Taurus fan. Thought I was all set.

When I opened the controller package, I find out it
will carry a max load of 30 amps, and I've read in one
place that the Taurus fan pulls about 33 amps on high.

Anybody know for sure?

I hope I didn't spend close to $100 for nothing!

33Amps..

The Ford Taurus electric fan is commonly used to upgrade the clutch fan in a jeep. They are known to draw upto 90+Amps on start up.

Then 33 continuosly. Fan Installation

[macx]

Right - found that out with some more
research.

I had to swap for the higher cap FlexALite
controller - which will hold 40 amps continuous.

It's a "soft start" which means it doesn't
have the spike at start-up - starts it up
more slowly to avoid the spike.

I've had that controller on for awhile now and
it works very well.

It's also variable speed, depending on how
much warmer the engine gets than the
on-temp I set it at.

[scot]

Where did you get the controller from?
thanks.

[macx]

Its the Flex A Lite variable speed controller,
got it thru Summit. Just under $100.
No relays needed.

They list 2 of them, it's a little unclear
about the way the capacities are listed,
it's the more expensive of the 2, and that
one doesn't come with all the wiring bits
& pieces that the other one comes with.

You can see instructions at
www.flex-a-lite.com
go to Automotive
go to Electric Cooling Fans
go to Electric Accessories
go to VSC Instructions

I bought the one with the kit, then got
to reading and found out what was what,
called FlexALite to verify which one I
needed and found that I needed the
larger one to carry the Taurus fan.

I wired in a LED in the dash to show
when the fan was running.
Green, 12volt (incl a built in resistor)
got it at Radio Shack, just a few $.
Powered it from the hot wire going to
the fan from the control, HAVE to hook
LED ground to the ground wire coming
back from the fan to the control
becuz hot is constant and the ground
is switched in the controller to turn the
fan on and off.

FAL was VERY good to work with,
made it right because of the confusion.

[58Chev]

macx,

Great info.

Are you using the dual speeds of the fan? Or have the controller on just one of the speeds?

[macx]

Being it's a variable speed, I've just got it
hooked to the high speed. The controller
slows it down as needed, but then it can
still run on high if necessary.

I don't know if the controller would run
a Mk8 fan or not - I know they pull
quite a bit of power.

[scot]

Hey, are other 2 speed fans any good?
I know that Olds cutlass Ciera with the V6 engine has a 2 speed fan, and I guess they are more available than the Taurus.
Thanks.

[58Chev]

Originally Posted by scrot

Hey, are other 2 speed fans any good?
I know that Olds cutlass Ciera with the V6 engine has a 2 speed fan, and I guess they are more available than the Taurus.
Thanks.

How big is the Olds fan?
Taurus / Sable 1994 - 1998 3.8L are plentiful in most if not all junk yards.
The blade width is around 16" and can pull a lot of air.

[macx]

I'm sure there are other fans that will work,
and of course it would depend on how much
power you're trying to cool and under what
circumstances - 4-wheeling would probly be
a pretty heavy cooling job.

I know the most air is pulled by the Lincoln
Mark VIII fan, but they take lots of amps.
Not sure if this biggest FAL would even do it.

There is another variable controller, but it's
$150 - I don't think it needs any relays either.
Lots of the hopped up Mustangs use that
controller and a Mk8 fan. Thought I had it
bookmarked, but will have to look for it.

The Taurus fan also, though pulls less than
the Mk8, pulls lots of air, reportedly enuf
to even cool blown hopped up Mustangs,
so figured it should be fine for mine.
Of course also depends if you're in
Minnesota or Florida! I just stuck with
what has worked for the hopped up
Mustang guys, so don't know much
about others.

[macx]

PS - The Taurus fan is 2" smaller than the Mk8
(I think 18" across?) and is a little thinner so
the shroud doesn't have to be trimmed.

Most guys have to trim the shroud on the Mk8
fan to get it thin enuf to fit, but it does cover
pretty much the whole radiator on a Stang.
The Taurus fan leaves about 2" along one side
and either top or bottom.