Ozz1967

iTrader: (4)

Hey guys,

84 T/A here with a mild 355 build motor in it. BeCool aluminum radiator. Air Dam is in good shape.

I'm looking at swapping my single electric fan out for a dual electric fan because when I run the AC, my temp creeps up into the red until the fluid boils. On the highway it stays cool enough and right about 200 with the AC on. The single fan just can't keep up with it. My single fan comes on when the fan switch tells it to, currently 195* for my Jet Fan switch. Also, the single fan comes on when the AC is turned on. There is no "dual circuit" like on the newers cars. It's ither on or off.

I've ordered a dual fan set up from a TPI car, mostly because I didn't want to fiddle with modding the shrouds that come with the LT1 and LS1 styles.

I was wondering, can I use that single circuit that's currently on my car to power both electric fans so they both come on at the same time (Using the factory fan connector for power)? Would this blow my relay/circuit? Or should I run the factory power connector to relay to start both fans? , should I tap the factory harness to run one fan, and then use a relay to power the second?

I'm looking at ease of use, which to me is both fans coming on at the same time with temp and when the AC is on. Other than using a controller to manually run the second fan, I don't know how else I'd get the fan's to run at different times (one fan with temp, both with AC etc). I don't even know how i'd get the secondary relay to know what the temp is...unless I slaved it to the AC circuit...now there's an idea.

Anyway, just looking for some thoughts on how to do this right.

naf

iTrader: (7)

You need two separate circuits, each with a relay. I pulled a dual fan setup and yanked all of the fan harness and relays. Ran the primary from my existing circuit and wired up one of the other relays through an adjustable controller to turn on a little later than the primary. You could do without the second controller and use the temp switch to engage both at the same time, but you'll still need a second relay.

Ozz1967

iTrader: (4)

So my existing relay could run one of the fans. I may hook that up for now because the single fan turns on with the temp and AC.

I'd then need a second relay, wired up to run either on a delay or different temp than the first? Sounds easy.Hmm....

naf

iTrader: (7)

I used the flexalite adjustable controller with the radiator probe. It's supposed to be rated to 20 amps to wire directly to the fan but the wire guage was much smaller than the stock stuff. I just used it to ground the stock relay and adjusted it to turn on about 10 degrees hotter than my primary switch (which is 185-190ish).

There's a 30 amp kit available that's a hair more expensive that would probably work if you don't have access to stock stuff.

Put a new radiator cap on too if the age of your current one is unknown. Could be your boil over problem right there. They don't last forever.

Ozz1967

iTrader: (4)

Which kit would you recomend?

The radiator cap is about 2 years old. Same age as the radiator (BeCool Aluminum radiator)

naf

iTrader: (7)

Haven't used any others but I'd go with any one that is rated at 30 amps.

Ozz1967

iTrader: (4)

Ok, I'll take a look on Summit.

carrelljustin

iTrader: (8)

Just got done wiring up duals in my buddies Blazer, and in my 89 RS. one of the easiest ways of doing it is to get the kit like NAF said. We bought two of them from our local parts store for $35. They come with a 40 amp relay so that you can do both fans off of one unit. The wiring is easy, and the instructions tell you where each wire goes. The ones we got even have a wire to go to the a/c clutch wiring so that when you turn the a/c on, the second fan will kick on no matter what. The setup comes with a probe that you place in the radiator fins, and is set to come on at 186 degrees, and turn off at 165 degrees. The other fan is adjustable by a little adjuster built onto the relay housing. Here is the kit we used, http://www.summitracing.com/parts/HDA-3647/. If you want the kit right away, most auto places carry it in stock.

Ozz1967

iTrader: (4)

Thanks for the look, I"ll definitely check it out. Looks like I"m only going to need one additional circuit though to run the second fan. I basically need it to turn on all the same times that the primary turns on...except later/higher temp.

carrelljustin

iTrader: (8)

If that's all you are wanting to do, just go get you a relay and some wiring. Not to hard at all. There are a few ways you can wire the second relay, just depends on how careful you want to be.

RS Chris

You could just wire the second up straight off the battery to a switch. You'll need a 30 amp fuse and relay, some wire, and a switch. It can be done in about an hour. This is the setup I have on my car, only thing is you have to remeber to turn it on in traffic. If you don't want mess with having to turn it on and off then one of the kits suggested with probe will work fine.

Ozz1967

iTrader: (4)

Ideally, it would only turn on when the AC is on, or if the temp goes over say, 210*. the first one already comes on at 195 and off at 185, and comes on with the AC no matter what.

one92rs

iTrader: (5)

here is the controller i have used on several projects. controls 2 fans and has the a/c signal wire. it also has provisions for switches that turn it on or off 100%. on the projects that had a/c i used the off switch on the freeway if i was going on long trips as the a/c was cooled with the iar coming in.

Ozz1967

iTrader: (4)

Did you forget to add an attachment?

1988GTA500HP

This is the one I got. Has a wire to connect to AC to turn on automatically when the AC is on.

http://www.summitracing.com/parts/DER-16749/

Ozz1967

iTrader: (4)

I know I'm bringing up a little bit of an older post here, but this will probably turn into one of my winter projects here. Could I hook up one fan of the dual fan setup to the existing single fan relay, and then add a power tap to the second? Tis power tap would be the trigger for an after-market relay which will then trigger and turn the second fan on? The second fan would have it's power tapped from either the battery or alternator.

This way I would have a dual fan set up that basically acts like my current single fan does as both fans would turn on at the same time.

naf

iTrader: (7)

Existing setup will certainly run one of them. You'll need a second relay and power wire for the secondary. You could easily tie the second relay into the stock fan switch lead to engage both at the same temp. I'd lead/lag them though. No sense the secondary coming on all the time.

Ozz1967

iTrader: (4)

What's the best way to delay it?

I was thinking to have them come on at the same time simply to make it easier to wire in.

articwhiteZ

iTrader: (56)

you can tie them in. to come on and go off at the same time.
just use a larger relay. to run the 2 fans. iv had mine set up like this for the last 17+ years.works Fantastic!

they come on when needed. and go off when not. clean simple and it works!

lingenfelter did this set up back in the 90's the car never got hot. even on a long race weekends..

Ozz1967

iTrader: (4)

This is what I will probably end up doing, is there any way to get a bigger relay that will fit in the factory location?

If not, I will have to run the second relay for the second fan, just tapping power for that relay to activate when the first fan activates.

formula1LE

iTrader: (3)

Here's a pic of a relay install I did on a set of LT1 dual fans. With my relay design, the fans run at 3 speeds-low, medium and high wiht AC clutch activation. The high speed relays are rated @ 50A and the other control relays are rated @ 40A each so this setup will run any single fan or dual fan setup. Eliminates voltage spikes, no more high amp start-up, etc. and all wiring is j1128 spec and all connections are soldered and heatshrinked. Best relay system anybody will ever find!

Ozz1967

iTrader: (4)

That is really pretty cool. Where do you get the power from in this set up? Factory harness or a separate power source?

formula1LE

iTrader: (3)

I run a stand alone power supply from either the battery or the 12V supply junction.

Johnny Blaze

iTrader: (15)

Are you selling this setup or can you show us a diaghram and parts? Cool setup!

formula1LE

iTrader: (3)

Johhny....I have 4 setups currently made up-I offer them for $159.99 each. A comprehensive wiring diagram is included with each kit. It's universal in that it will power any single or dual fan assembly. Or, I have one LT1 fan assembly left if anybody is interested-$279.99 for it and my relay harness is presided to it just like the one in the post.

Ron U.S.M.C.

If you want to run/add a single fan than this is the circuit I suggest . It uses an adjustable fan switch but the switch is connected between the ground wire coming from the relay and the grounded spot. This way you don't need to be concerned about running the fans amperage through the switch. It’s a completely separate circuit from your stock fan wiring so if you use large enough wire and relay this circuit will control the largest single fan you can put in. The circuit shown below is running heavy gage wire and a high amp relay to control a large high AMP fan. That may not be necessary running an average fan. I use a 30 AMP relay and 14 gage wire from the battery terminal to the relay to the fan including the fans ground wire. 18 gage for the ignition sides of the relay.
If you want a second fan you can install another controller and relay and wire it in the same way.
That's exactly what I did and it works flawlessly.
http://www.autozone.com/autozone/par...67187_69565_0_

formula1LE

iTrader: (3)

The idea behind my kit is that it eliminates being restricted to only one fan speed-high. You usually don't require high speed very often and, it saves wear on the fan motor and charging system. Not to mention les fan noise while running at slower speeds while keeping the engine cool. No other relay kit can offer this flexibility.

Johnny Blaze

iTrader: (15)

Like this
http://www.jegs.com/webapp/wcs/store...=&pgGrp=search

formula1LE

iTrader: (3)

The F150 Lightning forum is littered with stories about their VSC shorting contacts and melting the unit with HO fans. Crappy tin alloy filler metals don't like heat it would seem. Not so with commercial grade relays however.

Ron U.S.M.C.

Not trying to take anything away from what you're offering because that's not really possible. Your kits are top of the line with quality parts and light years ahead of anything I can build.

That being said.
There are many items that I won't use because I hate working with the electrical aspect of my build. Another member here showed me where the flaw was in the cercut I was using to run a adjustable fan in my car.It was my first attempt to create a cercut that had the adjustable switch and was user friendly ( simple to wire in). He showed me the circuit above and one using the ground wire going to the switch in the head. ( The switch in the head being replaced with a adjustable controller ) It is the simplest of the two.

Talk about simple. These circuits are as basic as you can get and only designed to perform one function. Installing an adjustable fan switch with a single fan. I've posted this information several times including the circuit created using the ground wire to the switch in the head and have never seen a reply from anyone concerning the use of either one.
I try to offer information on this site that is simple, accurate and usable.

formula1LE

iTrader: (3)

I agree 100% with you, Ron. There are times when a tried and true basic kit can fit the bill. And I do like one controller on the market-DC Controls above all others but I realize (because I myself am a builder/fabricator as well) that one always tends to want the flexibility of upgrading should the need arise. For a fairly low amp, single speed fan, there is nothing wrong with a basic fan kit.

However, there are intrinsic differences with all temp sensors or switches. The radiator probe style can be off as much as +/- 10 degrees and the country of origin oftentimes determines the quality of the unit. Temp switches which thread in are in the range of +/- 2 or 3 degrees and actual sensors are +/- 1 degree and offer the greatest accuracy. I also like to try and use parts you can get at any parts store or even a GM dealer for that matter should you run into a problem. But, you don't always have to go with a comprehensive fan kit but once you have the top dog, it can be scaled down just easy as its ability to be scaled up with respects to running HO fans. To each there own though....sometimes simple is better.