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Electric fan

skinny mike

Supporting Member
Supporting Member
Posing wiring question. My fan came with a temp switch, for the intake water crossover, that creates a ground when it's temp is reached. So...if I wire that to the fans ground wire, then wire the fans positive ( with fuse) to a battery hot source I should have a working auto on-off fan. Right? Then...if I wire in an on-off toggle switch, one wire spliced to the ground and the other to ground I would have a manual on, right? It would make the ground should the temp switch fail.
 
G'day Mike,
That's correct, however I would use the sensor to ground a relay and use the H/Duty contacts in the relay to drive the fan. An override switch in parallel will give you the manual control.
Regards,
 
Have you got a link to the fan kit?

You might want to add a relay in your circuit.

The temp switch usually isn't made to actually switch the current that the fan motor draws, unless it's a smaller one, at least not without eventually self destructing.

Let the temp switch activate the relay, which can carry plenty of amps for the fan motor and increase your overall reliability.

The over-ride toggle switch you mention should be in parallel with the temp switch, and would manually pull the relay in if switched "on".
 
Well..don't know electric theory. Need road maps to follow.. No idea what a relay does so am out of my depth here. Isn't the two pole switch, spliced to the sensor wire and the other pole to ground in parallel, not series? I have a diagram showing the on/off switch wired thru a relay but, it's for when the a/c kicks on. In a bucket? So..i am thinking no need for that relay..wrong I guess. BUT...no a/c to affect the function so...confusion. The motor isn't ready to fire yet, so tried the switch and nothing.Can jump the fan to the batt and it runs so, that wire is ok and also the ground. Back to the garage, pull each wire and check for continuity. SIGH!.
 
Well..don't know electric theory. Need road maps to follow.. No idea what a relay does so am out of my depth here. Isn't the two pole switch, spliced to the sensor wire and the other pole to ground in parallel, not series? I have a diagram showing the on/off switch wired thru a relay but, it's for when the a/c kicks on. In a bucket? So..i am thinking no need for that relay..wrong I guess. BUT...no a/c to affect the function so...confusion. The motor isn't ready to fire yet, so tried the switch and nothing.Can jump the fan to the batt and it runs so, that wire is ok and also the ground. Back to the garage, pull each wire and check for continuity. SIGH!.


Your concept of the toggle switch wired in parallel with the temp switch/sensor is correct.

In brief, a relay is an electrically operated switch that uses a small amount of current, (less than an amp) to energize the coil of an electro-magnet that moves a set of contacts that are capable of switching many amps.

The most common auto relay usually has a common contact (COM) that's connected to the normally closed contact (NC) when the relay is not energized, and then connects to the normally open contact (NO) when the relay is energized. . . The 2 coil connections make up the other 2 pins.

There are some auto relays that lack the NC connection so just have 4 pins total.

Usually these common automotive style relays are rated at 40A, which while it seems really high, keep in mind that a motor draws at least 5 times, or more, amps when it starts than when just running.

No doubt some one has a good link to wiring a fan relay they'll share.
 
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Well, Island Girl, ain't you sumpthin! Wish you lived next door. Be glad you don't!!! Thanks for the feedback! Need, now, to really start digging.
 
That's right how mine is hooked up , main reason I couldn't get to the front plug in manifold
 
Island Girl is a wealth of knowledge. She knows more than a lot of guys and has a real class way of showing it. She does not brag but is able to express and teach in a very classy way. My hat's off to you Island Girl!

Jim
 
Well.. checked my wiring and it's as the diagram in the link AusBucket posted. No relay for the manual override switch.. I must have a bad crimp or something cuz, no fan when I switch on ignition and toggle the manual switch. Can jump the fan to the batt and it runs. I just love these electrical thingies. NOT!
 
If you have an ohm meter to check continuity, start at one end of the fan over ride circuit
and work you way back to the other end checking at each connection. If you are wired correctly,
you must have a bad connection. and you will get infinite resistance at some point. Everywhere
else you should only see a couple of ohms.

Sorry if you already know all this.
 
A picture is worth 1000 words:
https://photos.app.goo.gl/hrTd15djhbz222D29

rhueeMjOl3oqxq0oexL6iCQ-BOKcrsb03SjPQPtHQuC7hmOaP0XW74xBxdwAXWUV1aEskuRQD8ll_FnU6TEMu3lXmEwTAWd5WOuu74UtEXMEYDGVjhDEcMW7GiZ7q3DtCRIapLF-km58x4BEyO8Wxt5tgU81WEBkfwdpXKIhuEphDysIA_GjREiQ8oD_hX0ndt_l5nKOLjhZakEKghTn8RL2s11o4oLsHOKudnYMe0_Hu2lemQ5npb9wU6ZOdJGGr-tl86lrYiZEfxTTCRryottaRE_4QZW1TU2-8cmUrD_AlZ98x_REAG7e_iofFEhMQxm8wvKVe5XX6bpVCBnVEUvGIZvFSRCitOHI7IK4YpIBAvJ-fwKKV8XTRW-H_vj54rvlOBPtCXLnYSad8vCyuVNfz6UvlVaPuw15zA-W3xRbX20XDY6cH18QWFxuMeEvkSFNVaTXRJ97izp9D0f0J9vO8kaOUqVotbxKhBFmUGVCtLWs32Sz2c_t_YPcRqvx5sT6oKK1i-Xy_xIfLCrcvYBqi9hSk-GH8Q-U8FPL834U8DVslXm_cP1hesoOb2mzd49BvvpwwA-VZ1qYa0rVnYSNNGyttovl0RP1Cs1InTPEJZVbfClTa0_A6FAazOUCvECgUGQbS941nJ4CSDIpbAqliTmk_dfRnk2Yc60NrDPWEiX7ihLVG-rjDVUGK-war5gvd2_i3iCFDPK37wPIXARy=w591-h285-no


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what size wiring to hook up the fan?

You will have two different sizes ..... one for the control circuit (relay #85/86 & switch) and one
for the power circuit (relay #30/87) to the fan.

You have to figure the distance for both directions, up to the load and back in the table below, even
if your frame is the ground circuit.

Ex. 20 amps and 10 feet, your wire size should be at a minimum 16 AWG, but I would go to the
next larger size 14 AWG on the power circuit. You don't want any voltage drop between battery
and the fan allowing the fan to give you the best possible RPM and cooling.

WireGaugeToAmpTable01.jpg
 
Any switch is fine. And I wouldn't use frame, motor or body for ground; I've seen enough ground problems to last my lifetime. Run ground wires to the temp sender and the fan. And you should get the fan power from a fuse. Big enough so it won't blow when the fan comes on. It's a safety thing; if a problem occurs the fuse blows instead of the wiring melting or the relay or fan smoking.
 
Pulling my hair. Couldn't manually power the fan.T he wiring is as some of you show. Found a popped fuse, rechecked my wires...all ok. Remembered I once had an old motorcycle that the ign switch went bad. The terminals on the back are kinda loose, old switch (as is the whole car) Ordering one from Speedway. I don't know much of the history but, it was sold back in 86.
 
PotvinGuy… if I am not supposed to ground to the frame, etc where do I hook the fan ground wire? To the temp sensor wire? Is the sensor the fan ground? My diagrams show a stand alone ground from the fan and the sensor a separate ground to the relay. The fan ground wired to the sensor is a "better" way? Hey...I'm open to improvements.
 
G'Day Mike,
If the original builder relied on frame ground then you (can) ground the fan at the frame. Just check you have good continuity back to the battery ground. The car should have a ground strap going from the BatteryGnd to the Frame and on to the motor (usually the starter motor mount), you could run the Fan ground back to that point.
Regards,
 

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