Wiring an electric fan. I am a novice with electrical

[crash89]

This will be a really basic question for most.. I am a novice on electrical.
I am getting ready to install an electric fan. Ground is not an issue. I have that figured out. On the picture I attached, where is the best place to connect the positive for a switched connection? The fan it will be controlling is 17 amps. I would rather not do a manual switch and really don't want to burn anything up. ;)
The car is a 69 Roadrunner. Any help would be appreciated.

 

[BeepBeepRR]

At 17 amps I dont think I would connect it directly to a 50 year old harness. They are pretty maxed out and most of the wiring will be smaller 16,18 gause wiring You could do a seperate harness for it and have it switched via a relay and stock switched wiring. Just basically closing a contact point in the relay. Then the heavier gauge wire just passes through with the lower gauge just closing that contact. Smaller load on the factory harness.

Crude diagram..

 

[crash89]

At 17 amps I dont think I would connect it directly to a 50 year old harness. They are pretty maxed out and most of the wiring will be smaller 16,18 gause wiring You could do a seperate harness for it and have it switched via a relay and stock switched wiring. Just basically closing a contact point in the relay. Then the heavier gauge wire just passes through with the lower gauge just closing that contact. Smaller load on the factory harness.

Crude diagram..

View attachment 752215

I hadn't thought about going that route.. That is a really good idea.

 

[BeepBeepRR]

You would need a make and break style relay for what I was talking about. Surely you would need at least a 20amp here is what I found on the web.
https://www.12voltplanet.co.uk/make-break-relays.html

And you can read about the style here.
https://www.12voltplanet.co.uk/relay-guide.html

 

[crash89]

You would need a make and break style relay for what I was talking about. Surely you would need at least a 20amp here is what I found on the web.
https://www.12voltplanet.co.uk/make-break-relays.html

And you can read about the style here.
https://www.12voltplanet.co.uk/relay-guide.html

I looked at this one... I think it is the same concept.
https://www.amazon.com/Absolute-RLS...relay+switch&qid=1555617857&s=gateway&sr=8-23

 

[Jerry Hall]

We installed a fan on the radiator of a 67 Charger the other day. His fan came with a 20 amp inline fuse. He didn't spring for the relay kit, so we ran it inside to the back of the fuse box and connected it to a switched 12V 20 amp circuit that used to power his rotating headlights motors which were disconnected because of bad motors. No problems or issues. The fan actually pulled 12 amps at startup and pulled 6 amps running. I see no issues with that.

 

[coronet68mx]

You REALLY need a relay for a fan, also remember, that the fan have 2 speeds, therefore the 2 87 terminal in the relay,
calling mi amigo Nacho @Nacho-RT74

 

[halojumper]

What beepbeeprr said relay the fan, or if you could afford it re wire the car fifty year old harness is getting a little toasty.

 

[crash89]

What beepbeeprr said relay the fan, or if you could afford it re wire the car fifty year old harness is getting a little toasty.

Honestly, I am glad he suggested the relay. I didn’t really want to splice into the harness or potentially ruin the wiring. The wiring is original and I didn’t want to take chances.

 

[67belvedere/225]

https://www.amazon.ca/MICTUNING-Fus...G+12V+Fuse&qid=1555632787&s=automotive&sr=1-1

 

[67belvedere/225]

https://www.amazon.ca/MICTUNING-Fus...G+12V+Fuse&qid=1555632787&s=automotive&sr=1-1

these relays are great , they come with the fuse in them

 

[halojumper]

Would Robert Yule have any wiring harness for fans? He did a great job on the headlight harness with the relays, and fuses.

 

[BeepBeepRR]

I looked at this one... I think it is the same concept.
https://www.amazon.com/Absolute-RLS...relay+switch&qid=1555617857&s=gateway&sr=8-23

Yes that would work. Its the same make and break i was talking about. This just bypasses a huge load on the wiring harness and could save you a crap ton of headaches. Then its easy to find a switched hot.

 

[crash89]

Yes that would work. Its the same make and break i was talking about. This just bypasses a huge load on the wiring harness and could save you a crap ton of headaches. Then its easy to find a switched hot.

Yep. I have a good switched hot. It was the load that concerned me. Using the relay solves the problem. I already have the relay coming and will make a harness to wire it up.
There is a ton of knowledge here. I really appreciate it!

 

[OH71RRunner]

Make sure you're relay is big enough to handle the initial startup draw. Some fans have huge amp draws at startup. Some relays will struggle with the load and eventually burn up.
I used heavy duty style relays on mine even with the controller. Mine was wired with a 3-way switch: auto, off, and high speed. (I had a 2-speed fan).

Also, depending on the controller, you may need an extra diode so the fan doesn't overcharge your battery. I added one for piece of mind.

I may have over-engineered my setup, but I didn't want to take any chances.

 

[BeepBeepRR]

You know, I didnt think of a thermal switch or some way to only run it when needed. But here ya go a thermal switch just wire it in with the power going to the fan from the relay. This way its not running all the time just when the car gets to a certain temp. https://www.amazon.com/American-Vol...ocphy=1015318&hvtargid=pla-653888257138&psc=1

 

[crash89]

You know, I didnt think of a thermal switch or some way to only run it when needed. But here ya go a thermal switch just wire it in with the power going to the fan from the relay. This way its not running all the time just when the car gets to a certain temp. https://www.amazon.com/American-Vol...ocphy=1015318&hvtargid=pla-653888257138&psc=1

View attachment 752421

Yup. That’s the diagram for the fan controller that I posted. I did not want it running all the time. I bought an adjustable one but will likely set it for 180 degrees.

 

[BeepBeepRR]

The one I posted a link to was 165 off 180 on. that would be sufficent.

 

[Nacho-RT74]

You REALLY need a relay for a fan, also remember, that the fan have 2 speeds, therefore the 2 87 terminal in the relay,
calling mi amigo Nacho @Nacho-RT74

Yes but no. Will need still to use two relays. The dual output relay can be still used to feed each one for each speed but will need one previous to switch on from ign switch and being sourced from alt post in 30 terminal, since the trigger signal ( 86 ) would come from temp sensor to activate the high speed maybe.

OR use individual relays for each speed, which is the more common way to use it, just like the tipical headlights relay upgrade.

Which will be mandatory is get the relays sourced from alt post, not from batt. And an alt able to feed no less than 45/50 amps iddling. The more, the better. Don’t worry about the ammeter range.

I can post a diagram later of couple of ways to feed the system.

( I don’t get why a diode has being suggested, no need for that )

 

[Nacho-RT74]

I’m at this moment checking the thread from the phone ( not at home ) and I’m a bit confused. Does the adjustable system get some temp sensor somewhere such as sender getting the water temp just like the gauge sender? Or just takes the temp sensing from engine bay on air?