Mine is fused, the install kit came with a pretty big fuse. It is also fused at the fuse panel for the sensor wire.
This is similar to the fan I have in my Ford, came with everything, good instructions. Take the Spal part number and go to Summit and you can download the instructions.
https://www.ebay.com/itm/30102048-16-SPAL-ELECTRIC-PUSHER-FAN-W-WIRING-MOUNTING-KIT-195FH-30130011/292455763273?epid=658469787&hash=item4417b8cd49%3Ag%3Abp8AAOSwiDFYQJ8O&_sacat=6028&_nkw=spal+electric+fan&_from=R40&rt=nc&_dcat=33600

 

The power demand for the cooling fan is too large to operate off the circuit box, Always use a relay with cooling fans.
The relay switches the power on and off to the fan, the 12VDC+ is sourced at the battery through a fuse (battery + is usually picked at the starter), the relay is controlled by the ignition switch and fan switch (fan switch is ground). The relay's coil draws very little current, sourcing its coil 12VDC+ through the ignition, with the fan temperature switch supplying the relay coils ground.

 

fan relay

I ran a single 16" fan with an off-shore high amp toggle switch and it melted. The box may say 50 amps but who knows what it will actually handle. Go with a relay.

 

Go with a 70 amp relay, they have larger supply/load terminals than the "standard" 30/40 Bosch style relay.

The larger relay may be overkill, but I have used them for over 5 years without any issues. I run a Mark VIII cooling fan motor and it pulls 65 amps+ at start-up. Good luck.

 

I didn't even know you could get a 70 amp relay! All I've ever seen are 30 amp.

Yes I would definitely use a relay. Most fan switches are not rated the current fan motors pull. You can wire it up however you want but I would use the fan switch to ground the relay. If the fan switch is a one wire, you would have to use the fan switch to ground the relay.

My Fiat Spider did not come with a fan relay from the factory. 15 years ago it got to where it was blowing fan switches every year. Probably because the fan was getting old and has electric motors age they pull more current.

It uses a 2 wire fan switch. Originally power went from the battery, through one wire, out the other and to the + side of the fan. They the fan motor was grounded. After using the relay to ground the relay, I haven't put a fan switch in this car in over 15 years.

I've since installed a larger SPAL fan but I am using the same relay and fan switch. It's probably pulling less than half the current as the original fan.

The fan switch for my Polaris Xplorer 300 is NLA so I drilled and tapped the mounting bracket for 1/8" NPT and used a universal 185F one wire fan switch. I initially just used it ground the fan but the fan pulled too much current and burned it out. So I had to order another switch and use a relay to ground the fan motor.

 

I didn't even know you could get a 70 amp relay! All I've ever seen are 30 amp.

her's a link to a 120 amp relay (they make them even higher)
https://www.amazon.com/ONLINE-LED-S...f=sr_1_20_sspa?ie=UTF8&qid=1531601386&sr=8-20-spons&keywords=50+amp+diode&psc=1

 

I have a relay 5 of them in fact. they have a one hole tab for mounting it.Where does one place a relay...i have never used a relay.wiring pattern would be nice to have.Would i just mount it close by the fan maybe on the core support ?or? thanks bob s

 

Would i just mount it close by the fan maybe on the core support ?or? thanks bob s

I mount my relays as close as I can to the fans. If your mounting location exposes the relay to weather/harsh conditions, use a weatherproof relay and harness plug.

 

I used this diagram as a guide but upgraded/upsized the supply/load wiring size to 8ga, so I would not have ANY power issues. As far as placement, place it where it is convenient to get to while keeping the wiring runs as short as possible and/or needed.

Note in the diagram the diode placed across the fans "+" and "-" terminals, this helps with voltage spikes or electrical feedback as the fan spins without being energized through the relay, I just used a readily available diode from a 90's Ford, part # F2TZ-14A604-A, that is easy to wire in due to it's terminal size. Hope this is helpful.

 

I wanted a picture [needed] of the schematic] No way would it work. just wants to save it.Then you can't find it.bad deal bob s

 

My relay is on the back side of the core support, fuse is close to the battery (this is why the supplied wire with it is so short...). Just apply common-sense wiring and you should be ok. My fan is rated at a 21 amp draw when it comes on, my relay is 30 amps. When it comes on my voltmeter drops to 13v. So it definitely taxes a charging system.

 

My default condition is to step up the wire gauge rather than add another failure point.

KISS, Keep It Stupid Simple, the anti-NASA philosophy of engineering.

Bogie

 

As i look at all the sendrs in the orelleys catalog. They show 2 bladed senders. Ihave A single bladed sender. and its not turning on the fan, A fellow said to me.I need a 2 top spaded sender to operate. the fan ~ the temp" and the ~relay. Should i just oder the installation kit from Summitt $30.00 or so. if it won't work properly.i can go to Dakota digital or Hotronics or Painless just not sure on this whole fan deal any more help please lmk before i mess up this brand new engine with to much heat thank you bob s

 

People actually shop at O'Reallys? You need to be looking at what the fan experts are selling like Hayden, Spal, etc. My sender is a single blade, my harness came with a wire that attaches to it.

 

i bought a Hayden fan.They should have the correct sender......................or am i missing something in your reply?? bob s

 

I should hope they have all that you need. You mentioned 2 blades on the sensor, you have double fans?


Here's their instruction sheets page, see if it helps.
https://www.haydenauto.com/Installation-Instruction Sheets/Content.aspx

I'm no electrical whiz by any means and I keep it simple. I bought my Spal fan on eBay with the works. It was a lot less expensive than what Summit wanted. Their site is not as helpful as the Spal site was. What is the part number of your fan?

 

NOW i find out the 3700 fans are packed as pushers and not pullers, kleenex stays attached to the front of the radiator when the fan does kick in the curved blades are turning clockwise! WTF i should jus bought A shroud and a regular fan. Darn it bob s this damn fans gonna kill me yet bob s

 

Some fans will work in both directions depending on how they're wired. Most of them will change direction if you flip polarity even if they're not designed to run that way. They probably won't last long that way though.


I'd double check that you've got it wired correctly and then check the fan documentation to see if it can be run the other way.

 

For a curved blade fan like below, counterclockwise should pull. Clockwise would push.

 

Thank you Tyler.Icouln't figure it out because of the swirl, Eventually maybe bob s