I'm wiring in my dual Spal fans, and one of the wires from the relay goes to an ignition source. It looks like the IGN on the fuse box takes an unfused spade connector. Does anyone see any problems with running the ignition wire directly to the IGN slot without a fuse? I'm assuming that, because the wiring kit didn't come with a fuse, it will be ok.

(Power will be directly to battery with inline fuse that comes with the kit)

 

You fuse for the size of the wire- idea is the fuse will blow before the wire melts and starts a fire.

That IGN terminal is fused at 20A- which means you should be running 12GA or larger (lower numerically) wire!

The orange wire ( as indicated in pic) doesn't need more than 1A of current to trigger two relays.
I'd fuse at 3A - close to the fuse box as that wire is probably 18GA- maybe smaller

Richard

size of wire and appropriate fuse size

 

I would fuse it..2-3 amp
maybe you have one or two that are fused? Cruise not used as in diagram for 79 is fused?
i have extra connectors if you like pm me address which one if u like
post 34
https://www.corvetteforum.com/forums...8-track-2.html

 

Very nice of you to offer that up!!!

Us guys that can't afford the newer vettes- pre-78- have ancient fuseboxes!!!

The other thing I forgot to mention-
The "IGN" terminal will power the fans in ignition AND start. Not good if you are trying to start the car and the fans are trying to turn on.
ACC is on in accessory and ignition but not start. So if your key was left in accessory- could wipe out the battery.

I actually use a relay so when starting- the fans won't turn on.

Richard

 

Use the yellow wire for the wipers. It is fused, is not powered during start. Solves all your issues at once. And it’s under the hood not in the cabin.

 

Some circuit s aren't powered when the key is in the crank position like the blower and wiper circuits.

 

Very generous offer. I just may do that.

 

Thanks for the ACC suggestion. Makes sense.

 

not having to go into the cabin sounds good.

just splice into the yellow wire for the wipers?

 

I ran a lead from the Selected Terminal (iGN/BAT/ACC) source to a Relay and then you pick a source to supply heavy load and put the fuse on the load side. .that way the only load on Selected Terminal (IGN/BAT/ACC) terminal is the relay. If you get an adequate relay you can put multiple loads on the load side as you deem necessary.

 

You would still need to fuse the trigger wire (orange) at the wiper- running a small gauge wire and fused at 20A- you risk melting and possible fire.

Correct- you have basically 2 ignition sources-

Power on- in ACC and ignition but not during start (wipers/radio- yellow wire)
Power on in ignition and start but off in accessory ( gauges-pink wire)

 

So a fuse is needed regardless. I'll go with a 3A as suggested.

Thanks to all in this thread. I really appreciate this forum, and those within it.

 

You are using the same fans that I use on my C3. I have it wired up thru a DeRale PWM Electronic Fan Controller which starts the fans at 50% and ramps the speed up as the engine gets warmer and if the temp drops the fans will slow down. The DeRale system works very well IF you wire it like they tell you to in their instructions. They tell you to set the set-point where you want the engine to run temperature wise and the controller will do the rest. I like that it will continue to speed up the fans until the engine hits the peak temperature and then they automatically slow down once the temperature starts to drop.

Having the PWM controller makes no spikes on your electrical system and A LOT LESS Noise when the engine is running. Being a bit paranoid I went ahead and installed the relays for the "back-up" system for my cooling fans. I have had a failure before on a fan controller so I now have a "back-up" system for the cooling fans. My little 427 gets hot sometimes and it needs the two fans to stay cooler. I was afraid that I would have another failure on a road trip so I installed a backup system. I now have a Holley EFI system and it will control the fans as well but it starts and stops at 100% speed. I will leave my relays and wires ready in case of a problem.

I have a Fuse inline with the relay's Power and another in each HOT wire going to the fan motors. I am using a 5 amp fuse for "relay power" and for the fans I have 30 amp fuses on each fan. I used the "Accessory" mode for power to activate the power to my DeRale controller as well as it is used to power the two relays in the backup system. Switching to backup would take just minutes as I have everything prepared for the situation.

 

yes. Have had mine that way for better part of 10 years. I don’t see the need for a fuse. The yellow wire is fused, should anything short that fuse will pop. If a person is worried about it then use a larger gauge wire to the relay than the yellow wire from the wipers. I used a slightly larger gauge than the yellow wire in mine. The trigger circuit is very low amperage can’t be more than an amp.
if you wanna fuse it then get an inline fuse and put it in.

you also don’t need to go in the cabin to get a battery connection. It’s at the starter lug.
fuses for the power to the fans could be problematic, start amperage can be pretty high exceeding the rating of the fuse. Look into short stop breakers.

 

I like the reduced load and noise aspects of your setup.

 

The positive lug on the alternator should work for power as well....correct?

 

I'm a fan (no pun intended) of the Derale PWM as well. It's about $180 at Summit and Jegs- easy to wire up- has a sensor you just stick on the radiator.

The positive lug on the alternator should work for power as well....correct?

There are those that will fight over where to connect the power for the fans. Since most cars have a battery under the hood- the go to would be the battery.
Why the battery? The battery is a nice -clean- voltage stable source to get the power.

Fact is- the fans usually kick on at idle- the alternator might be rated for 140A- but that's usually at 1500-1800RPM depending on the pulley set-up.
So at idle- the alternator might be a third to half the rated output- and of course the rated output is at 70ºF- and puts out less as the alternator heats up.

So connecting to the alternator is definitely not the best spot-I don't recommend- as when the fans start up- the alternator almost sees a dead short- as that's when the fans pull the most current-

And depending on the year of your car- the electrical system was woefully equipped to handle much more than the high beams at idle.

A real catch 22 situation.

Here's what I recommend- it's not that expensive to do it right the first time- but get pricey doing over again and frustrating-

-Upgraded Alternator
-Upgraded charge wire from alternator
-Check and if needed improve grounds and battery wire
-power connections & distribution

There's a lot of good alternators out there- come a long way in 40-50 years. Don't necessarily look for the one with the most output but output at idle.

Charging wire- you can see in the other chart- how much current wires can handle- 6GA is a good choice.

The battery wire is (70 and earlier are 2GA) 1gauge- which is a good size.

The starter lug will work fine in a C3- close enough to the battery.


Here's a couple of diagrams- I like (and others here) the Blue Sea Marine terminals and fuses. Quality made and stainless steel- but not ridiculously priced.

The last pic is mine- made a post to use just in,case I needed to jump start- a heck of a lot easier than behind the seat.

 

Richard thank you very much for the detail explanation. My Vette is 1980. I have a new Powermaster 140 amp. I'm following the advice given and wiring power to the starter lug.

 

You are welcome!!!

Richard

 

I wired mine straight to the alternator. I also wired in an override switch under the dash.