I would like to know where is the best place to tap into ACC Power besides the wire going to the radio.

The reason I'm asking is because I am putting in a third fan with a manual switch. Mainly, so I can run it when the car is off.

Thanks in Advance,
Jay

P.S

Last time, when I had it hooked up to the ACC power wire going to the radio the volts decreased from around 14V to either 9V or 10V. Is that normal or should have something else to protect the circuit?

I have an 140amp alternator.

 

The best way to do what you are wanting to do is to use a relay. Use ignition power to triger the relay and bat power to power your fan. You can use the wire from your radio to power the relay since it does not require much power to click the relay, but you really need to use a relay to power the fan. If you need help wiring a relay up let me know and i will try to talk you through it.

 

Brad RS,

Thanks for the help.

I pretty much know how to wire a relay. Although, I just need to know what time of relay I should be using? (NO SPST SSR). Since a relay is actually a switch will wiring it this way take away my ability to control it manually?

If I wire the relay to ACC power that will allow the fan to run continously while the key is in ACC?

What if I were sitting in heavy traffic on a hot day and I wanted to turn on my third fan? If I had it wired to the acc that would not be possible, correct? However, if I used the ignition power to trigger the relay it would run continously all the time, which I don't want. Is there anyway I can have a happy medium besides using a manual switch?

Thanks,
Jay

 

Think of the relay as not automatic, its switched by you. But you don't want full 12V and 100+ amps going through a little wire to only a little tiny connector in your switch. Instead the switch in your car turns on the relay, which turns on your fans.

It's almost as simple as taking constant power from the battery, directly to the relay. Then the switch itself can be powered by any wire you want in the fuse box, just like your radio switch. Cause it'll only use a tiny tiny amount of juice. Then you run the wire to the relay, and from the relay to the fans.

I'm not good at drawing a wiring diagram. But it's 100% possible, and probably a lot easier than you're thinking it is.

 

I believe I kinda understand what your saying. However, I'm just confused about one thing. My manual switch has three prongs. One for ground, + fan, and power.

I know that the power will be coming from the fuse box. I know what ground is for. However, since I will have the relay wired to the actually + side of the fan. What do I wire to the + fan on the switch?

Could you tell me whether or not I'm on the right track with this diagram?

Thanks,
Jay

 

So keep in mind I'm not the most mechanically inclinded person, so I would get someone to confirm my post before you go out and follow it.

But in the pic above...

+12V - to battery
Ground - to ground
20A inline fuse - I would fuse it, but not sure on what amps you would want in there
To Switched power - I believe your switch will have the constant (+) coming from the fuse box to one terminal. And the other terminal goes out to the relay. So the switch only has (+) running through it.
Power to accessories - To the fan
Bosch relay - The relay

So that's what it would look like if I did it personally. Hopefully someone can validate that for ya.

 

that seems like the right idea.

i would pick a wire or connector in the fuse block that gets power at whichever key position you want. run a wire from the fuse block to the switch. (this is the power into your switch). then run a wire from the other terminal on the switch to the power-into terminal on your relay. then connect the relay ground terminal to a ground or make your own.

the next part would be to run a wire from your battery or constant power on the fuse block into the relay. then take the last terminal and run a wire to your fan or tap into one of the wires leading to the fan.

this all should work providing your fans are power controlled and not ground controlled. I would think they should be power controlled just just take a look at the schematic to be 100% posative

so things should work like this: when you flip your switch this will bring power to your relay. the windings in the relay create a magnetic field which pulls a metal bar to give continuity to your wire from the battery(this is why you hear the clicking sound when the relay is powered on). so essentially think of the relay as an electrically controlled switch.

Hope this will help out

 

Switch
Terminal 1- Power from fuse block
Terminal 2- Wire to terminal on relay (power into)
Terminal 3- Ground ( Unsure, since you said something about only + thru the switch)

So should I just get a two terminal switch?

Relay
1. Constant Battery Power
2. Power in from switch (Terminal 2)
3. Ground
4. Power to fan

On my 91' z28 orange should usually be hot at all times and pink/blk should be ignition hot, correct?

What size inline fuse should I use?

Last question where is the best place to purchase one of those relays?

Thanks for the help guys,
Jay

 

i dont kno bout your exact switch but ive used some that are lighted and the ground is usually there to light the light.

that realy set up sounds right and you can get one at Advance or carquest for a few bucks.

the other thing to pay attention to is your wire diameter. as for the wires thru the switch they should be bout 16 guage or so. and for the fan; try to match the same diameter as the wires already running thru the fan.

for the fuse: just use a fuse appropriate for the switch. most switches have ratings on them. I did a starter cutout switch for my car using a relay set up like what we've been discussing and i didn't even bother using a fuse

 

May I ask why?

JamesC

 

Don't forget that running the fan without the engine running, won't cool down the engine at all. The fan will just blow a minor amount of air around your engine bay. And since the waterpump don't be moving, the cooled off fluid in the rad will never reach the block.

Peace.

 

I actually want to use the extra fan on those extremely hot days and if I ever happen to be stuck in traffic or something of that nature.

I know the fan won't cool engine down significantly and I also know that the water pump will not be pumping. However, it will cool the fluid in the radiator faster. Therefore, the next time I drive it my fluid would be much cooler which in result will help the engine to cool faster.

Jay