Wiring a switch to manually control the fan

SteveMat

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Has anyone rigged up a simple switch to turn on the radiator fan. I think it would be handy to be able manually kick on the fan when sitting in traffic or preparing to go down the 1/4 mile.
 

Hostile

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SteveMat
Good idea I did just that, used the "mystery switch"on the dash
with a relay located down by the heater motor where the cooling
relays are located,works great.

Skeeter
 
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SteveMat

SteveMat

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What are the chances of you posting out what parts you used and some directions for us electrically challenged? Do you make it so you could control the fan speed (Hi/Low)? Also, I don't have the mystery switch so thoughts on what I could use?
 

David

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I just blip the A/C on momentarily. The radiator fan continues to run for a few minutes. I haven't timed it, so I don't know how long it'll run, but it generally outlasts a red light at a busy intersection. Hope this helps...
 
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SteveMat

SteveMat

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Cool, I am also reading in the 97 Service Manual and it says the "relay entergizes when the PCM provides a ground to the relay....."

So in theory to test that I have the right relay; I could get a piece of wire, attach one end to the relay and the other to a grounded piece of metal in the engine compartment and the fan should kick on.

Assuming it does I could do some of mentioned ways of hooking up a simple toggle switch...
 

prodiver

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I put a mini toggle switch in the air duct under the steering wheel to turn mine on and off. Works good and it is out of sight.
 

VIPER1996

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Hostile, I would be very interested in hearing a little more detail about how you wire the fan with the mystery switch. Thanks Brett
 

WESTCOAST JASON

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The low fan is what is run when you turn on the A/C - in addition to the the fan goes on low at 207F and off at 201F. The high speed fan runs when 216F is reached and kicks off when 208F is reached. Fans turn off at 77mph or under acceleration. Back on at 67mph. Now as far as a switch here is what to do.

Open up the small cover forward of the fuse box under the hood. It will have 3 relays in it. The relay that is most forward and drivers side is the fan on relay. Remove it and you will see numbers on the pad it plugs into. Number 96 (most forward one) is the lead you will ground to manually turn on the fan. You can put a piece of wire in the 96 hole (stripped) then reinstall the relay. From there route the wire to a switch that grounds when thrown and you are done. You can make it key on always by using a relay in place of the switch and have it provide ground when key is in the run position. Anyhow - CYA

BTW: I need a flex pipe from someones stock exhaust. (cheap please) email [email protected] if you have one. thanks
 
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SteveMat

SteveMat

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Almost 4 months later, I give this a run. When I hook up a switch to Number 96 of the relay, everything works as expected and the fan turns on while the switch is enabled. Problem is that the "Check Engine" light has come on. Thoughts on why that would occur? This is a 97 GTS.
 

HP

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The PCM monitors the relays and it's possible that any manipulation of the
stock relays will throw a code. Basically the relays are the only function of
the cooling fan circuit that is monitored, as such- you can loose power to the main fan power circuit and not throw a light. There are a variety of setups
for manually controlling the fan - grounding the switch for the fan relay sounds like the simplest(unless you want to power the fans with the key off)-
but you run the risk of throwing code lights.
 
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SteveMat

SteveMat

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I pulled the Airbox cowling and blower off looking for the radiator wire. Am I missing it?

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motomike

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Life is easy with Sean Roe's fan switch and timer. Beware that you don't want to run the fan for long, long periods when the car is just sitting off to avoid wearing down the battery.
 

HP

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I pulled the Airbox cowling and blower off looking for the radiator wire. Am I missing it?

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The fan wires run from the fan motor to the PCM - which I assume for a 97GEN-II
is next to the brake reservoir in front of the driver firewall. On the GEN-I,
the PCM is on the passenger side - and that makes the fan circuit a weak link.
Look at your manual or check with someone that has a manual for the correct
color and PCM pin location - or PM me and I'll give you the info(I have a 97
powertrain manual)
 
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SteveMat

SteveMat

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Thank Hugh,
I am looking in the 97 Service Manual and it states -

"The radiator fan relay is located below the heater blower motor housing...."

I am guessing this is something that was missed when the updated the Service Manual for the GTS's.
 

HP

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Right, to get to the relays you remove the blower intake housing(easy) -
but the only reason to access the relays - would be to replace or test them.
If you want to switch the fan with the PCM grounding wire - the easiest place
is at the PCM connection - you can find the grounding wire for the 'fan on', and
the 'high speed' - in your manual. Then all you do is connect a wire from the
grounding signal wire to a manual switch that connects to a ground.
Another way to manually control the fan motor is to run a + wire off the
battery jumper post(driver side) to a relay then connect it to the fan power wire(at the fan motor)- the relay will need a + and - connection, and can
be switched by either.

I have a GEN-I - which has a longer fan circuit which can hardly handle the amp
draw of the updated 99 fan - so I completely re-did the high speed circuit,
Now my high speed circuit runs directly thru a 10g wire, straight from the
battery jumper post - and is switched by an added relay next to the fan motor
by the former power wire. I also added a manual high speed switch - so
I can turn the high speed on anytime - even when the car is turned off.
 
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