Electric Fan Wiring... Thoughts... Opinions

[Slammed84]

Getting close to being able to mount the radiator support. Need to run the wiring first for my electric fan. I don't have the option of using the temp switch because someone glued in the plug on the intake.

Probably just run it through a switch under the dash.

Need thoughts about using a relay or if it needs a fuse, or if I can just wire the power through the switch and turn it on as needed.

[Remon.]

Always on a relay. Use the plug in your block (passenger side between 8 and 6). This also gives you a more accurate reading.
+ from your battery to the relay, temp switch to you relay and one cable from the ignition switch to the relay. Then one from the relay to the fan. Try a Google search to get the drawings.

Did you make the shroud yourself? Pretty cool, I made it excacly the same a year ago.

[Slammed84]

Originally Posted by Remon.

Always on a relay. Use the plug in your block (passenger side between 8 and 6). This also gives you a more accurate reading.
+ from your battery to the relay, temp switch to you relay and one cable from the ignition switch to the relay. Then one from the relay to the fan. Try a Google search to get the drawings.

Did you make the shroud yourself? Pretty cool, I made it excacly the same a year ago.

Do you mean the plug in the cylinder head?

The port on the drivers side is going for my temp guage.

I had it wired correct on my last 350 but I sold off that intake.

Never even thought about there being a port there between 6&8.. duh!

[Slammed84]

The whole electric fan kit came from summit, so did the radiator. I still have the relay and instructions

[school boy]

This is what im doing with mine.
Im using a fan from a previous project. Its enough for the tiny 305.
Summit fan relay kit. Its nice with extra wiring, inline fuse and most of everything you need. Just remember to get the correct temp sensor for your thermostat.
I also bought a gm junction post, mine was for a corvette but buy to suit your needs. I needed this for all the extra electrics like my fans, air compressor for the helper bags, and the small amp powering 4 6" speakers.
I still have to straighten things up but you get the main idea.

[S10Fan]

Not really an answer to your question, but this is a great resource for most any 12 volt project..........

http://www.the12volt.com/

My electric fan is wired through a 40 amp relay and a 30 amp fuse. The relay gets it's ground from an intake mounted temp switch.

[Slammed84]

So I pulled the plug out of the passenger side cylinder head. Now I need to find an adapter for the 3/8NPT temp switch I have. It is a Summit brand 185 ON/ 175 OFF. The plug looks like 5/8NPT or close to it.

I'm thinking with the way my headers sit, it would be smarter to run the temp guage from the passenger side and run the temp switch on the drivers side to avoid burning up any wiring.

When I bought the fan kit it came with a relay, circuit breaker, wiring, and instructions ( so i can rewire it correctly ).

[dwcsr]

Originally Posted by Slammed84

So I pulled the plug out of the passenger side cylinder head. Now I need to find an adapter for the 3/8NPT temp switch I have. It is a Summit brand 185 ON/ 175 OFF. The plug looks like 5/8NPT or close to it.

I'm thinking with the way my headers sit, it would be smarter to run the temp guage from the passenger side and run the temp switch on the drivers side to avoid burning up any wiring.

When I bought the fan kit it came with a relay, circuit breaker, wiring, and instructions ( so i can rewire it correctly ).

You need a brass 1/2 ntp to 3/8 ntp bushing, available at any home store or hardware store

[gmachinz]

Here's a few fans I've built and installed on some squares....the relay kits I build myself and are 3-speed and fully automatic using 2 GM style temp switches.

[Slammed84]

So I just got back from O'Reilly and picked up the 1/2''-3/8'' NPT bushing.

I snapped a few pics of everything.

The yellow wire is supposed to go to a fused 12V source, but I'm almost certain that before when I had this wired up, I just plugged it into a keyed hot source on the fuse box. Is that the same thing?

But by looking at the pictures it looks like for some reason I had it connected to something else with a butt connector? I can't remember, its been awhile.

What is a good fused 12V source to tap into without having to splice into the factory harness? I would like to avoid that if possible.

[school boy]

I ran my temp switch in the tpi manifold (up front). But my temp guage sender came factory in the driver side head so that's where it stayed.

[Slammed84]

@gmachinz

thats a pretty intricate setup there

[gmachinz]

I have tried over the years all the various aftermarket "controllers" and never really found a reliable one...mainly because I prefer Motorcraft style OEM Ford fans which even by Spal's own account are way more stout than anything offered by anyone else. Problem is, most people try to run these high output fans with single relays which work, but can be loud after a while and the constant off-on-off again cycling will prematurely kill the fan windings and it produces crazy voltage spiking to the relays.

I decided to design a fan control system using simple but stout commercial grade relays, a series of resistors and 2 GM temp switches to allow me to have up to 4 fan speeds that can be used with any DC fan...single or dual. I've been installing these for about a year and a half and it is virtually indestructible and the best part is all the primary working components can be parts store or dealer sourced should you ever have a fan problem on the road. That is a feature nobody else can offer.

[Slammed84]

Originally Posted by gmachinz

I have tried over the years all the various aftermarket "controllers" and never really found a reliable one...mainly because I prefer Motorcraft style OEM Ford fans which even by Spal's own account are way more stout than anything offered by anyone else. Problem is, most people try to run these high output fans with single relays which work, but can be loud after a while and the constant off-on-off again cycling will prematurely kill the fan windings and it produces crazy voltage spiking to the relays.

I decided to design a fan control system using simple but stout commercial grade relays, a series of resistors and 2 GM temp switches to allow me to have up to 4 fan speeds that can be used with any DC fan...single or dual. I've been installing these for about a year and a half and it is virtually indestructible and the best part is all the primary working components can be parts store or dealer sourced should you ever have a fan problem on the road. That is a feature nobody else can offer.

That's cool man, I'll have to hit you up when I get my big block built and get everything done right. My goal right now is to just get this thing back on the road and slowly address things that need to be done.

I never had any trouble with it before. I used one of those 160 degree thermostats that have the bypass built in and it ran cold. Half the time the fan wouldn't even kick on. It did however not run as well unless it got up to temp so this time I will be using a regular 180 degree t-stat and the temp switch is 185/175 on/off.

The fan is pretty loud but I like it that way so I know its coming on. Another thing I liked was when I took it to the drags I could pop the hood and just leave the key on and it would cool off a little better.

[gmachinz]

If that is a standard 5-pin Bosch type relay, I would suggest swapping that one for a better quality one. If its A Summit brand its probably Chinese and the diagram on it shows a very basic circuit that unfortunately does not include a 100V resistor or diode across the relay coils. Even with a fairly light duty Spal fan like you are running, you should run a high quality relay. A great, great relay to use in place of that one can be found at junkyards on a variety of Volvo 850 and 950 series wagons from about 1994-up. Look underhood for a relay/fuse panel, open it up and look for black relays labelled with a big white J. They are rated at 40A but can handle up to 50A for short periods and they feature parallel resistors and diodes. Those relays even used are way better than probably 90% of the EBay relay fan kits.

I use diode equipped relays and I add them myself in certain situations within the harness. I find a lot of European vehicles are pretty stout when it comes to electrical systems.

[Slammed84]

Originally Posted by gmachinz

If that is a standard 5-pin Bosch type relay, I would suggest swapping that one for a better quality one. If its A Summit brand its probably Chinese and the diagram on it shows a very basic circuit that unfortunately does not include a 100V resistor or diode across the relay coils. Even with a fairly light duty Spal fan like you are running, you should run a high quality relay. A great, great relay to use in place of that one can be found at junkyards on a variety of Volvo 850 and 950 series wagons from about 1994-up. Look underhood for a relay/fuse panel, open it up and look for black relays labelled with a big white J. They are rated at 40A but can handle up to 50A for short periods and they feature parallel resistors and diodes. Those relays even used are way better than probably 90% of the EBay relay fan kits.

I use diode equipped relays and I add them myself in certain situations within the harness. I find a lot of European vehicles are pretty stout when it comes to electrical systems.

what does one of your kits run, price wise?

[gmachinz]

And don't use thread sealer....it can interfere with the ground reference signal for the temp switch. If the bushing is NPT as well as the switch, you shouldn't need it.

[gmachinz]

I've just completed a large stock order so I have been offering them for $149.99 plus shipping. I also stock New aluminum t-stat housings with dual ports for temp switches-its kind of an accessory item for my fan kit since a lot of people have problems finding a good place to thread the switches in. If you have and are using ported vacuum switches for emissions controls then this wouldn't be a feasible option but if that's not a concern, then this setup is pretty much a bolt n go deal.....and the best part imo is it appears factory. No goofy controller that gets "revised" every year, replacement parts literally can be found anywhere, and it converts any fan or fans to multiple speeds.

[gmachinz]

Here's the t-stat housing kit...available seperately from the fan kit.

[SkinnyG]

I snagged a relay from the wreckers off a Sunfire/Cavalier - the late 90's up have a recall for their starter wiring bursting into flame, so GM plunked in a hefty relay that handles a lot of current.

I have this relay feeding a dual fan set off a Ford Windstar. Fits the factory rad dang near perfect, but the two fans draw a lot of current.

I took a fan switch from some 80's 2.8L GM V6, which I screwed into the passenger side of the head like you did.

[gmachinz]

Yeah Ford imo have designed the most robust fans over anyone else. Siemens built the fan motors and Ford designed the shrouds. If you have really huge fan requirements, the 2010 F150 trucks have dual 16" fans in an enclosure that pull a whopping 6,000 CFM combined and it measure 19" x 38" x 6" mounting area! I have one setup to test my resistor harness and it controls them perfectly fine except I had to upgrade my high speed bypass relay to a 100A 4-pin relay with dual sets of diodes and resistors to handle the spiking when the fans went from high to medium speed or from high to off. Massive is an understatement.

[nekkidhillbilly]

Originally Posted by gmachinz

Yeah Ford imo have designed the most robust fans over anyone else. Siemens built the fan motors and Ford designed the shrouds. If you have really huge fan requirements, the 2010 F150 trucks have dual 16" fans in an enclosure that pull a whopping 6,000 CFM combined and it measure 19" x 38" x 6" mounting area! I have one setup to test my resistor harness and it controls them perfectly fine except I had to upgrade my high speed bypass relay to a 100A 4-pin relay with dual sets of diodes and resistors to handle the spiking when the fans went from high to medium speed or from high to off. Massive is an understatement.

these trucks for the money you can use lt1 ls1 gm 3.8 fans or even tpi fans. there all about the same and fit the radiators. unless you have a diesel then you want two ford 3.8 fans.

[nekkidhillbilly]

you can one that goes in the fins of the radiator had one on dads truck for years. i recommend a derale. had a flex a lite one it was junk and melted lasted about a month. derale has been on there for 6-7 years at a least.

[Slammed84]

so anyone got any good ideas on how to tap into a fused 12v source, something that won't be seen and won't require cutting into the factory harness?

[nekkidhillbilly]

on my 01 i used just a fuse tapper under the hood for a key. hot source went to batt. ground went to factory ground had to cut the ac wire solder them in. i think though the 80s trucks have it all under the dash still could just wire through one of the groments and use a fuse tapper in the block.