matt smash

I replaced my single radiator fan in my 86 Iroc with a dual fan setup from an 88 Iroc. The 86 is carbed, (fyi. Don't think it makes a difference), and am trying to figure out how to get it to work. One should turn on for the motor and the other for the ac. I think

Ozz1967

iTrader: (4)

In a single fan set up, the one fan is controlled entirely by the fan switch in the passenger head of the car. Also when the AC is turned on the fan will turn on.

In a dual fan car, the primary fan is controlled by the ECM and the secondary fan is controlled by the fan switch.

For you to do the conversion properly, you need to wire in a second relay.

Alternately, you can run a separate fan control relay for both fans.

A third way to do it is what I will try to do. Run the primary fan off the relay that's in the car. THis fan will operate just like the single fan that you replaced. You then tap the power lead from the factory relay (*the one that goes to the fan itself) and run it to a second relay that engages the second fan the same time. This way both fans turn on and off at the same time. The power for the second fan will be tapped either right from the battery or from the alternator. Essentially the power going to the new secondary relay activates the new second relay, which switches on to pull power from the battery or alternator. This way I don't overpower the factory relay in the car by trying to turn on two fans.

Johnny Blaze

iTrader: (15)

Can you just unplug the single fan harness and plug in the dual fan harness?, Provided you have the proper sensors in the engine?

Ozz1967

iTrader: (4)

You can plug it into one of the fans, not both. you will need a second controller for the second fan. The single fan set up cannot carry the amperage required to run two fans...you'll melt wires and blow the relay.

Johnny Blaze

iTrader: (15)

What people don't seem to realize is the Dual Fan wiring harness has the relay in the harness.

The Factory engine harness has the same plug for single fans or dual fans.

Camaros have a seperate fan hanress that plugs into the main harness.

The Single fan harness is simply two wires that plugs into the main harness. The relay for the single fan is in the main harness.

The dual fan harness has the same plug as the single fan harness on the main harness end. From there it has the high amp relay and the plugs for both fans.

It seems to me that GM would have made one main harness, and the single or dual fan harness was then plugged in later down the assembly. This would make sense as to why the fan harness unplugs from the main harness.

Thoughts?

Ron U.S.M.C.

Johnny,
Where has that information been hiding ? I've never read anything about it.
Really good stuff .

Im going to add it to my extensive archives.

Side note = Going from single fan to dual fans in this manner, what does the ECM think about this ?

Ozz1967

iTrader: (4)

What I was talking about was simply installing the dual fan's and bracket with the two plugs for the fan's while using the original single fan harness.

You can't adapt it to plug both fans into the single fan harness because you'll melt the original wiring.

If you swap the entire harness over, then it will work.

The main problem with this is that the ECM in a single fan set up doesn't control the fan, only the fan switch does. Which is why you either need to run a second relay or wire up both fans to come on when the single fan did originally.

Johnny Blaze

iTrader: (15)

So the single fan cars have a different ECM?

The entire engine harness is different for a single fan vs a dual fan, not just the removable fan harness?

MY-92-RS

iTrader: (3)

I cheated... bought this fan contoller at pepboys it is fully adjustable has a themo couple that is in the rad fins I have it set to come on at about 185 works great had it for several years now runs booth fans at the same time .

Johnny Blaze

iTrader: (15)

Hawks seems to agree with me judging from the "conversion" they sell.

http://www.hawksthirdgenparts.com/pr...eover-Kit.html

Ozz1967

iTrader: (4)

My single fan car does not use the ECM to run the Fan. I have 1 relay for 1 fan and it doesn't run through the ECM, it runs through the fan switch. I have no provision for two fans. There is no extra wiring. It might be different for later models when they started putting the dual fan's in cars (86+), I don't know.

Ron U.S.M.C.

This can be used to wire in the first fan (or any fan)and is the easiest way I have seen to wire a adjustable fan switch in. You simply take off the wire that goes to the switch in the head and ground it to the car. Than just cut that same wire (let’s say in the middle) and install the thermostat controlled switch in-between those same cut wires. Run the probe to the radiator, set the dial to where you want it and you're done. Anyone that has a switch in the head can use this method and have an adjustable fan.(The proper thermostat will be determined by what temp you want your fans to run at.)
If you want to know how to set the fan temp switch quickly then just ask.
http://www.autozone.com/autozone/par...67187_69565_0_




The next easy way to wire in a adjustable fan switch is to use this completely isolated circuit. It does not use any of the stock wiring and can be used to control a second fan.
This way you can set the fans at different "on" temp. If you want.
I have two fans wired in this manner
Side Note =This circuit can also be used to run a high amp. fan using heaver wire and a higher amp relay.

JamesC

iTrader: (5)

Here's what I did with my carbed car which was originally equipped with a belt-driven fan.

https://www.thirdgen.org/forums/cool...electrics.html

JamesC

Tombowman89

New Hawks kit link is https://www.hawksmotorsports.com/dua...ProductReviews

it’s a Maradyne product