Almost every automobile manufactured
today uses an electric fan for cooling the radiator. For
the Mustang, Ford went this route in 1994. The electric
fan uses less horsepower than the mechanical fan,
helping both gas mileage and acceleration. You know
which part interests us.
We came across an
interesting alternative to the costly aftermarket
electric fan kits; a junkyard fan out of late 80's,
early 90's Taurus cars with the 3.8 liter V6. It is a
two speed fan with integral shroud and a low-profile
electric motor. One Mustang owner is using his on a
supercharged 302 without any problems. Sounds like it
should be able to handle our naturally aspirated 302. We
headed to the junkyard to find our diamond in the
rough.
Once in the Ford section of the yard, we were nearly
overwhelmed by the site of so many Tauri (plural for
Taurus, isn't it?). We chose an '89 wagon with the 3.8L
V6 as our donor. A few small bolts and one unplugged
connector and the fan slid out easily. We also pulled
out over a foot of the harness with the mating connector
and cut the wires so we would have plenty of length and
a nice weatherproof connector.
The price? A mere
$27, including the $2 entry fee.
With our dusty
treasure in hand we headed to the local chain autoparts
store for a controller and a mounting kit. See side bar
for required installation components.
Installation The stock 5.0L clutch fan and
shroud were removed and we laid the new fan in place to
check the fit. The shroud covers over 80% of the
radiator
Junkyard Electric
Fan : Parts List |
Fan |
3.8L Taurus |
$25 |
Imperial Controller |
PN: 3647 |
$36 |
Imperial Mount Kit |
PN: 226201 |
$6 |
Bosch 150amp Relay |
PN: 0 332 002 156 |
$30 |
Freewheeling Diode |
PN: 1N5408 |
$5 |
and sits nicely on the existing mounting clips at the
bottom of the radiator. Two "thru-core" connectors would
be needed to secure the top of the fan shroud against
the radiator.. To insure a good seal at the edges of the
new shroud we used foam weather seal you can find at any
hardware store. The pictures tell the story. It will
also protect the radiator from rubbing due to vibration.
With the fan in place we connected the cut
harness we saved and tried out the fan by going across
the battery with the bare ends of the wires. The low
speed wire contacted the battery post and the fan spun
up quickly. The airflow felt very good. If this was the
low speed setting, what would we get from the high
speed? We wish we had CFM ratings for you, but we could
not find them in time for this article. We can tell you
that with the high-speed wire connected the fan was
moving a huge amount of air. Far more than the last 16"
electric fan we bought from the auto parts catalog.
Since the fan controller has only one relay we
decided to run just the high speed, which should insure
a cool radiator no matter what. But before the wiring
can begin the charging system will need to be upgraded.
The stock 75amp alternator will not be able to handle
the added load of the new fan, especially after we saw
how much air it can pull. You can check out the 3G
alternator upgrade here.
Using a Fluke
digital clamp ammeter, we tested the starting (or
inrush) current draw and the operating current draw. The
Taurus fan pulled a little over 130 amps on startup
(only for milliseconds) and settled down to right around
40 amps using the high-speed wire. This is why you must
upgrade to the bigger alternator and a Bosch
high-powered relay.
Fan
Wiring Diagram
The diagram
shows how to use the fan controller to fire the Bosch
relay. A reverse current blocking diode (or freewheeling
diode) is a good idea on any motor control relay. Once
power is removed from a DC motor it becomes a DC
generator and the reverse voltage spike can shorten the
life of the relay. The diode will bleed this spike to
ground. The 1N5408 diode can be found at any electronics
store for just a few dollars.
The fan
controller also has a lead that can be connected to the
air conditioning compressor clutch power wire to turn on
the fan whenever the A/C is turned on. If you wish to
have a manual control switch for the fan, simply connect
it to 12V and contact 86 on the Bosch relay.
The last step is to set the electronic thermostat for
proper operation. With the engine running at idle, we
let the temp gauge slowly climb. We adjusted the small
potentiometer on the controller so the that the fan
would come on just before 200*, which is after the
coolant thermostat opens (180*, in our case). This way,
if you are cruising down the highway and the thermostat
opens but the radiator does not reach 200* thanks to the
steady airflow, the fan stays off.
Results So, how does it work? We decided to
really test it by driving 6 hours one way in 100*+
temperatures and race at Los Angeles County Raceway in
Palmdale, CA. That is desert country west of LA. Not
only did it work, but the temp gauge never went past ½
scale. Even letting the car sit intentionally for over
40 minutes with the A/C blasting while we packed up
after the race in over 100* heat the gauge not only was
stable but dropped to only about 1/3 of the scale! The
A/C actually blows colder than before, even when the
mercury goes past triple digits (way past,
occasionally).
Another pleasant side affect has
been a 1 to 2 mile per gallon increase in fuel economy
on the highway. The fan isn't running while cruising
unless you turn on the A/C. And then it cycles with the
A/C clutch. In conclusion, the time and cost were
absolutely worth it. We can also run the fan in the
staging lanes by turning the ignition to the on position
and switching on the A/C. Just don't forget it's on and
kill your battery. We had to get a push start in front
of all the other racers…
Source for the Bosch Relay-
Brandon Products Group,
www.bpg-inc.com
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