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Discussion Starter #1
The control module for the electric fan on my '69 Camaro is wired to get its' power directly from the battery(wire connected to the positive battery cable). I have read threads where the horn relay can be used as a power source. I would like to change the wiring of the control module as it is only a few inches from the horn relay. Would the correct way to power the control module consist of hooking up the power lead to the side of the horn relay where the red wire is attached as in the photo below.........


Thanks in advance for the assistance, it's greatly appreciated.:yes:

David F.​
 

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You can hook up to either that post or the one with the black wire. Or to prevent any shorting of the system. Run through a relay that way it won't take your whole electrical system down with it.
 

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Discussion Starter #3
You can hook up to either that post or the one with the black wire. Or to prevent any shorting of the system. Run through a relay that way it won't take your whole electrical system down with it.
Thanks for the info Brandon:yes:. Any recommendations on what type of relay????

David F.
 

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Discussion Starter #5

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I agree with Dale. While you could use the horn relay, the 8 ga wire to the horn relay is supplying all power to the vehicle. When you add the 30 amps or so drawn by the fans, you're likely to see some voltage droop and some heating of the wire between the battery and the horn relay.

Your wiring looks very nice. If you still have the junction block behind the battery on the radiator support, tap in there with an eyelet terminal and a piece of fusable link. Install a self reseting circuit breaker in the same general area and use that power supply to feed the fan relay. That'll keep your main power feed isolated from the high current of the fans and be plenty safe.
 

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Discussion Starter #7
I agree with Dale. While you could use the horn relay, the 8 ga wire to the horn relay is supplying all power to the vehicle. When you add the 30 amps or so drawn by the fans, you're likely to see some voltage droop and some heating of the wire between the battery and the horn relay.

Your wiring looks very nice. If you still have the junction block behind the battery on the radiator support, tap in there with an eyelet terminal and a piece of fusable link. Install a self reseting circuit breaker in the same general area and use that power supply to feed the fan relay. That'll keep your main power feed isolated from the high current of the fans and be plenty safe.
Thanks for the recommendations Dave!!! This looks like the best way to proceed.

David F.
 

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Discussion Starter #8
I need some advice in regards to how I need to wire the fan control module to function with a relay. I used the recommended link containing this diagram to create a schematic of how I believe I need to wire my fan control module.......................


Based on the diagram above,this is how I "think" the fan control module should be wired.............



Wiil this work?? Do I have to connect directly to the battery,or will a connection at the junction block suffice?? Where in the circuit would the fusible link and self resetting circuit breaker be installed?
Thanks in advance for any/all help,it's greatly appreciated:yes:.

David F.
 

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I'm not sure you need the relay in that setup. The fan control module is the current handling device so the relay isn't needed (I would think). You definately wouldn't want the relay connected to battery power at the fuse block since it'd be on all the time. The fusable link and breaker would be installed where you show a 20A fuse.
 

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Like a couple of guys already said, it would be best not to use the junction. The cable feeding it was sized for the amperage load of the original accessories on the car and I figure that in those days they weren't sized for add-ons. By connecting to the junction, you're adding on a 15A or so draw to that cable and may overload it if you have a lot of accessories running at the same time. That could melt the cable insulation or burn the cable.

When I installed a Flex-a-Lite fan in my truck, I ran 10AWG cable from the battery to an auto-reset circuit breaker to the fan supply. Then I used an unused fused circuit at the fuse panel to supply the control voltage. All you need is either the circuit breaker which the kit should have come with OR fusible link OR a fuse. Using a combination is redundant.


I need some advice in regards to how I need to wire the fan control module to function with a relay. I used the recommended link containing this diagram to create a schematic of how I believe I need to wire my fan control module.......................


Based on the diagram above,this is how I "think" the fan control module should be wired.............



Wiil this work?? Do I have to connect directly to the battery,or will a connection at the junction block suffice?? Where in the circuit would the fusible link and self resetting circuit breaker be installed?
Thanks in advance for any/all help,it's greatly appreciated:yes:.

David F.
 

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Discussion Starter #11
I'm not sure you need the relay in that setup. The fan control module is the current handling device so the relay isn't needed (I would think). You definately wouldn't want the relay connected to battery power at the fuse block since it'd be on all the time. The fusable link and breaker would be installed where you show a 20A fuse.

........so where I indicate a connection to "ignition or battery power" at the fuse block, it should be replaced by a connection to the ignition switch??, or can I just power the control module with 8 gauge wire from the battery and be done??

David F.
 

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Does your fan have a temperature sensor?
 

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Yes, it installs into the upper radiator hose and is connected to the control module in my diagram.

David F.
OK. You need at least two 12V supplies.

One is the high current supply that is going to run your fan. That is the one that needs to come directly from the battery and have 20A protection (circuit breaker or fuse) or whatever your documentation states.

The other is control voltage for the circuit board which comes from a 12V supply that is switched, i.e. on with the ignition on. It only needs to be a 5 amp circuit. With it being a switched circuit, your fan cannot run with the ignition off. You should also fuse it to be safe. Make sure it is an independent circuit and not shared. My Flex-a-Lite control board was dirty as hell. I used a 12V signal from several places and had things like ABS lights come on or the windshield wipers start running when the fan would kick on.

If you want, you can wire in a switch to turn your fan on and off as you see fit on either the A/C circuit or the manual switch circuit. The A/C one is usually wired to the A/C condensor clutch signal line so that when the A/C kicks on, the fan comes on. Your switch circuit should also come from an ignition switched source so that if you accidentally leave it on the fan doesn't run.

The controls are in your fan box. When the temperature hits your set temperature, it uses a transducer to close the contacts of the low current 12V signal which is the coil of the relay supplying the high current 12 volts from the battery to the fan.
 

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Discussion Starter #15
I'm not sure you need the relay in that setup. The fan control module is the current handling device so the relay isn't needed (I would think). You definately wouldn't want the relay connected to battery power at the fuse block since it'd be on all the time. The fusable link and breaker would be installed where you show a 20A fuse.
...Oops!! I should have stated "Switched 12 volt Source"



Like a couple of guys already said, it would be best not to use the junction. The cable feeding it was sized for the amperage load of the original accessories on the car and I figure that in those days they weren't sized for add-ons. By connecting to the junction, you're adding on a 15A or so draw to that cable and may overload it if you have a lot of accessories running at the same time. That could melt the cable insulation or burn the cable.

When I installed a Flex-a-Lite fan in my truck, I ran 10AWG cable from the battery to an auto-reset circuit breaker to the fan supply. Then I used an unused fused circuit at the fuse panel to supply the control voltage. All you need is either the circuit breaker which the kit should have come with OR fusible link OR a fuse. Using a combination is redundant.
.......currently wired to the battery and has a fuse,but I like the idea of using the circuit breaker.

OK. You need at least two 12V supplies.

One is the high current supply that is going to run your fan. That is the one that needs to come directly from the battery and have 20A protection (circuit breaker or fuse) or whatever your documentation states.

The other is control voltage for the circuit board which comes from a 12V supply that is switched, i.e. on with the ignition on. It only needs to be a 5 amp circuit. With it being a switched circuit, your fan cannot run with the ignition off. You should also fuse it to be safe. Make sure it is an independent circuit and not shared.
....control module is currently wired as you describe above. My thoughts for using a relay in the circuit is to reduce the load on the (brand new) wiring. Are my concerns of using a relay in the circuit unecessary???

David F.
 

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Yes. The 12V ignition source voltage is only control voltage for the fan circuit board. You're talking less than an amp draw. The control box is essentially already a relay. It is used just for switching the high current supply for the fan motor.

The 5 amp circuit I was talking about was to fuse it at 5 amps in case of short circuit.
 

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Discussion Starter #17
Yes. The 12V ignition source voltage is only control voltage for the fan circuit board. You're talking less than an amp draw. The control box is essentially already a relay. It is used just for switching the high current supply for the fan motor.

The 5 amp circuit I was talking about was to fuse it at 5 amps in case of short circuit.
Thanks!!!!!!!:beers:.

David F.
 

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Steiner said something about not using the junction block. I think he meant the horn relay buss bar which is the main power distribution point for all vehicle power. Personally I'd get your 12V hot feed for main fan current from the junction block which is located behind the battery on the radiator support. That keeps the high current load closest to the battery and should eleviate some of the noise issues Steiner mentioned having with other accessories.

Seems like your schematic may be missing a couple of circuits? I don't see a temp sensor and no switched power separate from B+ power. Then again, I'm not all that familiar with the control module you're using.
 

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Discussion Starter #19
Steiner said something about not using the junction block. I think he meant the horn relay buss bar which is the main power distribution point for all vehicle power. Personally I'd get your 12V hot feed for main fan current from the junction block which is located behind the battery on the radiator support. That keeps the high current load closest to the battery and should eleviate some of the noise issues Steiner mentioned having with other accessories.

Seems like your schematic may be missing a couple of circuits? I don't see a temp sensor and no switched power separate from B+ power. Then again, I'm not all that familiar with the control module you're using.
Good observation Dave:yes:. I omitted that when I made my schematic......
See if this is better!!!

The temp sensor is a small copper tube with a bulb on the end and it installs into the upper radiator hose and is controlled by the control module.I didn't think it was necessary to show that on the schematic,(as it's not technically electical connection on the outside of the controller,it is probably an electrical connection on the inside of the controller),should it have been included??

I sincerely hope that I have not caused unecessary confusion in any of my preceeding posts:eek:. I'm just trying to eliminate any potential short circuiting situations or damaged wiring.

David F.
 

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If you have a 3 wire charging system, the horn relay or bus bar is exactly where you want your load carrying 12 volt source to come from. The reason is, the charging systems voltage sensing wire comes from there, and if you don't hook your fan power there (not the 12 volt switched on wire that activates the controller), the charging sytem will not be able to maintain a consistent 14.2 volt reading @ the battery. The 10 gauge wire that comes off of the alt for charging is 10 plus feet long to provide a voltage drop so the system maintains the correct battery voltage. Read this link below and it will explain in more detail how this works. Mad electrical is badd ***, and all of their recommended upgrades work flawlessly. It is worth your time to educate yourself on how GM charging systems were designed and the results their engineering provided. Don't just stop with this article, go read all of their tech pages, follow them to the letter, and you will NEVER have a low voltage problem. Hooking it up as suggested will create problems you will not solve by trying a higher output alt, the single wire units being the worst because their voltage sensing comes from the internal voltage regulator where there is never a load to respond to. Anyone who tells you that mad's methods don't or won't work, doesn't understand Automotive electrical systems, and by doing things everybody else does never solves their problems, they only cover them up by taking voltage readings in the wrong places, or by hooking power draining accys like fans to a place where the charging system can't respond to the load to maintain your battery voltage at 14 plus volts... Trust me, I have been doing advanced auto electrical diagnosis and problem solving for over 30 years. I would not recommend something I can't back up with facts and I have done 30 or more hot rods using their methods, and can make a 63 amp 3 wire charging system outperform a 100 amp single wire unit every time... and will bet money on it and win. :yes: If you already went for the 100 amp single wire alt, then you essentially went hunting and shot your dog... The only way to correctly regulate voltage @ the battery when using high current drawing accys is by taking advantage of a remote voltage sensing charging system. Single wire 110 amp systems work well with no accys, (I.E. on a tractor with no accys) or in a car with no electric anything...

http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml
 
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