Wiring
In A Fan Control Relay(s)
by Martin Bokesch
I
have installed a relatively clean system to control one fan on my T/C. There is
no reason, as you will note further down, why it cannot control both at the same
time, or with an additional relay control both separately. I wished to be able
to control the upper fan with a switch, as the lower unit will come on if you
activate the A/C. My application
was to attempt to leave the unit as stock in appearance as possible but have
additional control. I have removed the cover from the fan and A/C control unit
on a number of occasions. Mounted on the right front inner fender, it is about a
couple inches thick and has a large wire harness that is held in place with a
single bolt in the middle of the loom to keep it attached to the controller.
This controller has the Fans, A/C, EEC and fuel pump power relays in it, so best
to leave the internals alone. I had to open it up as I had a poor pin connection
once and opened it up to do a Repair. One thing I noticed is that Ford used
Bosch relays in the controller. I’m a fan of Bosch relays, and have used them
extensively in the field on heavy equipment, (Mechanic by Trade). The wiring
that leaves the control relay is relatively light, so as we get into this, you
will find that Ford actually spliced 2 outputs together to feed power to the
fans from the controller.
The
rundown. I purchased a Bosch relay, Part #0 332 019 150, 12volt 30 amp. They
come in many types, but the basic version, can handle 30 amps, more than enough
for both fans if required, has connections for a main power feed, noted as #30
on the relay itself. There are 2 switched power out connections noted as #87 on
the relay and then there are the control power connections themselves, noted as
# 85 and # 86. The reason for the choice of this model is that is has a molded
in mounting bracket and is a well-sealed version of their basic model.
The relay itself is simple enough. Run
the main power supply to spade connection #30. Splice into the fan connection
from one of the 2 #87 connections they are both the same internally so either
spade will do. Connect a control (on/off) switch to the #85 spade connection and
simply connect the #86 to ground. Simple enough, took me about 4 hours!
I cannot stress the importance of good
electrical connections. The Bosch relays have an option of a push in style base
mount, or just an integral mount, which I chose to use. At any rate, All the
connections I made, including the female spade terminal connections are soldered
after light crimping. All splices were soldered and sealed with a dab of
silicone than taped to stop moisture from getting to expose copper wiring.
First line I pulled, a 10 gauge red wire
from the starter solenoid, positive battery connection side. I installed a 30
Amp self resetting Cole Hersee circuit breaker right at the relay, using a metal
strip drilled to fit the relay stud and the “”Input side”” of the
circuit breaker, The circuit breaker will be marked as to input side and power
out side. This allows for a rigid mount, and the plastic cover that the coil
also sits under on the driver’s side fender well will cover this. Ford put
enough loom and wiring in these beasts to cover half of North America. I had no
trouble routing the wire from the driver’s side all the way around to just
below the control module on the passenger’s side and stayed in a loom all the
way. This wire is the main feed to the Bosch Relay.
I than ran a light, 16 gauge, wire from
the dash (I ran a coated double line, in case I wanted to do an additional
connection of some sort in the future), from my dash switch also terminating
with a bit extra at the passenger side fender well. In order for this unit to
work, I located a Key switched power line under the dash and used it to feed the
dash switch. As the Bosch relay uses about .2 amps to run, any feed line would
work. It has been a while since I did mine so I cannot remember the exact line I
tapped, but it was I believe the Sound System feed for the Equalizer, which I do
not have, so it was open line.
All the wires end up below the
controller on the passenger side fender well, just in front of the strut tower.
This is also where the main connections to feed the fans are located. I
removed all the goodies from the fender well to allow access to the little bit
of space between the airbox and the tower. I mounted the Relay in this location,
as it looks stock, buried enough to look like it belongs there. I traced the
wiring from my fans back to the connection below the control modules, and found
the Ford has 2 wires from the module for each fan feed. These wires are spliced
into one feed in the harness just prior to the fan connection plugs. The fan
feed positive feed wires are both brown, the primary fan has a yellow stripe and
the secondary has an orange stripe in the Brown. I simply, but carefully
stripped the outer cover off the brown feed wire for my primary fan, as I only
did one fan, just back from the connection, carefully wound a new piece of
matching 12 gauge brown wire and soldered it, piggy back onto the original. Once
it was neatly sealed and retaped and put back into the harness loom, the other
end of this line also ran to the relay mounting point. The relay itself has all
male terminal connection on the bottom. I terminated all leads using soldered
female spade terminal connectors. The fan feed plugs into # 87, the power feed
into 30 and the control switch wire to # 85. When mounting the relay, run a
short piece of black wire from terminal # 86 to the mounting screw for
the relay, as the relay requires a ground line. Gauge is not important, as this
is just a .2 amp circuit, so 16 gauge would be lots. If you wish to control both
fans with one switch at the same time, just repeat the splice with the second
fan wire and connect to the open #87 terminal on the Relay, as there are 2 power
outlets on the rely. If you wish to control them separately, you need to run 2
switches, 2 relays, but the wiring would remain identical in both cases.
Why I did the job this way! I wished to
have additional control over the fans, as we all do. I also wanted to keep
things looking stock. The additional point was that it should be able to remain
operational as built, as I am not the only driver in my family, and if someone
does not turn on the fans, no problem, the stock system is still in place and
still functional. The additional switched circuit that I installed is piggyback
to the original, causes no feed back to the control module, as it is all
connected downstream of the original relays. The reason I used Key switched
power under the dash for my small control line is that when I or others turn the
car off, if the manual fan switch is left on, the relay will turn off with the
key and the fans will not stay running.
As you can see, there's not a lot of
wiring schematic to get into, as you are running all new lines, and other than
tapping into the existing fan feed lines, not really using any of the original
wiring. I did stay in the looms
with all the wiring, and it kept the appearance neat and tidy, so other than a
spare switch I mounted under the dash, just above the throttle pedal, one would
never know that the systems exists.
Again
I stress enough the need for good electrical connections, and using a circuit
breaker or 30 amp fuse in the main feed to the Bosch Relay, to protect the feed
circuit.
It
main not be as simple as a lot of the other post, which say just use big wires
and big switches. After being in the trade for 25 years, I have learnt the
correct ways and what works and survives. Although the fed line is longer than I
like, there is no strong feed available on the passengers side unless you wish
to tap into the control module feed, and I thought best leave this alone, as it
could get expensive if a short occurs.
Martin
12/16/00