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"How To" wire dual fans with on/off/automatic toggle switch
Posted 14 February 2004 - 08:28 AM
for those trails and days your engine just needs a little more cooling air to be sucked through. or those hard days on the trails in the hot weather.
for water crossings and deep water forgings. to help eliminate the possibility of breaking a fan blade and putting it through the radiator. also to help keep the splash down on the engine or near the intake.
for your day to day usage.
the really great part of how this diagram has you wire it is. you never will have a dead battery cause you left the fan in the on position. by running it off of the coil to activate the relays. it causes it not to be able to work unless the key is in the start or on position.
hope you enjoy or this helps you out. let me know what you think.
go to subaru modifications, then to the fan modification. too lazy to link it
Posted 14 February 2004 - 09:19 AM
If you want the "off feature"
Run the tank switch contact that now goes to the relay to the other pole of an "on-off-on" type switch.
Posted 14 February 2004 - 10:18 AM
Posted 14 February 2004 - 11:07 AM
Posted 14 February 2004 - 06:37 PM
yes the way you have yours sean is perfectly fine for how and where you use it. my car always had a problem of getting very hot. so i need them on all the time from time to time. extra cooling in warm weather. i'll find where i have that diagram. and i'll put it on there too.
if i may i'll add that diagram to my web page if you don't mind. tell me if you do and i'll remove it. thanks.
Posted 14 February 2004 - 11:00 PM
Posted 15 February 2004 - 12:26 AM
Posted 15 February 2004 - 01:26 AM
Your relays are ground side switched, but they control the power to the fans since they are on the "upstream" side of the motors. Hence, not ground side switching.
Posted 15 February 2004 - 02:54 AM
either way you are throwing all the voltage at the fans. the only differance is the voltage on the relay. but no matter what the amperage on the relay will be the same. beings the fact relays are rated at amps for a reason. cause that's the main reason they break down, open or short across.
a little note on how electricity works.
voltage is eaten up by the resistance. it should be to approximately 0 by the time it reaches ground at the end of a circuit. amps stay the same in a circuit all the way to the ground. amps create heat which heat kills electronics. hence why we use relays. if we didn't use relays you'd fry those little toggle switches to kingdom come. cause the heat from the amperes will fry them.
if you need me to post up the naval and civilian publications of electricity basicis and formulas i will. but i hope i need not.
Posted 15 February 2004 - 03:18 AM
Posted 15 February 2004 - 03:30 AM
Posted 15 February 2004 - 03:57 AM
I would agree that it probably doesn't matter to those fan motors, since they are quite beefy electrically, but I usually like to err on the side of reducing as much stress as possible on components. And yes, closing a switch on the power side does send a spike, however small, since the voltage was not previously present at the motor. Closing a switch on the ground side results in no spike since the voltage is already present at the motor. It is my assumption that that is why the factory wiring is set up that way.
I also don't see how putting the relays on the ground side complicates the wiring at all. They are merely being connected in a different location.
Posted 15 February 2004 - 04:17 AM
sensors on a car you might want it switched on the ground side. but overall you are not gonna kill the fan easily.
one of the main reasons i see that they actually use a ground for the switch. is because that's the easiest way to use a thermalswitch. unless you run power to your radiator and then out of it. using an insulator around the actual thermoswitch. inner conductor being power out and and outer conducter being power in. which would be a lot more complex. the way they have it is one gnd coming in sitting there. and when the semiconductor breaks down it grnds out on the radiator.
it's the same design that they use in engine bay fire wire in the aircraft. breaks down gnds out and turns light on. it's just utilizing the thermal switch.
Posted 15 February 2004 - 04:33 AM
Posted 15 February 2004 - 04:42 AM
Say you've got a fan wired with the switch on the ground side. If you were to take your voltmeter and place one lead on the positive side of the motor and the other to chassis ground, it would read battery voltage. Take that same fan and put the switch before it. If you do the same thing with your voltmeter, it will read nothing.
There does not have to be current flow for there to be voltage present.
Posted 15 February 2004 - 04:45 AM
it's voltage potential that always sits there. it just needs a ground for the circuit to complete and the current to start to flow.
Posted 15 February 2004 - 05:08 AM
Posted 15 February 2004 - 12:51 PM
Posted 15 February 2004 - 06:05 PM
Posted 21 June 2016 - 12:00 PM
Posted 21 June 2016 - 06:21 PM
What is the purpose of a relay? Can't you just toggle the ground side and run a new power wire with an online fuse?
The purposes of the Relay are (among others) to let the Thick wiring on the engine bay, to bear with the high voltage / amperage \ heat; while you send only a "signal wire" to the interior. Doing that, will elongate the lifespan of the system, including the Switch itself; also the Fuse lines for the circuit remains on the engine bay, adding safety.
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