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Radiator Dual fan wiring high/low relay

winreboot

winreboot

Experienced Member
Joined
5 September 2000
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684
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Replacing single fan with dual fan sounds like easy weekend job but found out that my fan's are only running at low speed and connection C225 in the sub relay box was fried/melted under the hood. It looks like the two new fans pull so much amp that it blows a fuse and melted C225. I just notice this after few months of driving.

Question?
Is it possible to have one fan ON with the low input and with high input both fans run or is there a way to buy pass the whole high/low thing and run the fans on high all the time. I run AEM stand alone ECU and don't know if the high/low can be controlled with AEM or is AEM just send signal to turn on radiator fan and the radiator fan module based on the temp will kick in the fan on low or high?

If anyone had wired dual radiator fans if you could please share how did you wire it, it would be great :)

Thanks in advance!

David
 
Do you know the power requirement of the dual fans? You can probably use a new relay for the fans and use the oem relays as a trigger.

Mike
 
The fans supposed to be 80W, 7 AMPS each. I wired them together and they connect to the same single cable. I was shocked how the C225 junction in relay box was melted. I think I'll use one fan for now and maybe try to control the other fan with AEM.

I just had no idea that there was high/low speed on the fans. I thought they were on high all the time when they turn on.

Thanks,
David
 
Yeah, the relay must have been getting very hot. Can you post a pic?

Adding a separate 12V 30amp relay would be the way to go and you can find a kit that includes the wiring. You connect the hot side to direct battery connection in the fuse box, the switched side to the fans and the trigger wire you can hook up different ways depending on how you want them to come on. I think you could find a relay kit at most any car stereo retailer.

Low fan relay operates the fan at low speed starting at 84C and when the temperature reaches 90C the high fan relay kicks the fan into high speed.




Mike
 
Last edited:
comtec said:
He just said the specs are 80W, 7 AMPS each :confused:


Mike
Click to expand...


I re-read that and now I am wondering what type/brand of fans the OP is using too :eek:

Mine were hooked by Shad at DrivingAmbition to run with dual speed. And I while I was told the 30 amp will burn I gave it a try and sure enough it did. So I have a 40 amp fuse now, and a spare one just in case.
 
I'm not sure how that happen my self but if others run dual fan's fine maybe something went bad with the fan motor. I got new Koyo radiator and will get new fan's to keep this all new and hope to install it this week maybe.

Here is the carnage of relay. Well I don't know if this was actually a relay as the top of it was RED plastic and all the relays are black. It look like just a junction connector but not sure.

IMG_0040.JPG
 
The fan in controlled by fan control unit, and has 3 modes, off, low and high.

Off is easy, the "fan low relay" turns on the fan ground through the resistor and the fan high relay turns on the ground with out the resistor.

Splitting the 2 fans and running one on the low relay and one on the high would help but the total draw may still be too much for the fuse.
 
winreboot said:
I'm not sure how that happen my self but if others run dual fan's fine maybe something went bad with the fan motor. I got new Koyo radiator and will get new fan's to keep this all new and hope to install it this week maybe.

Here is the carnage of relay. Well I don't know if this was actually a relay as the top of it was RED plastic and all the relays are black. It look like just a junction connector but not sure.

IMG_0040.JPG
Click to expand...

I think you melted the junction connector.
 
Briank said:
The fan in controlled by fan control unit, and has 3 modes, off, low and high.

Off is easy, the "fan low relay" turns on the fan ground through the resistor and the fan high relay turns on the ground with out the resistor.

Splitting the 2 fans and running one on the low relay and one on the high would help but the total draw may still be too much for the fuse.
Click to expand...
According to BrianK, It sounds like the circuit is controlled via two different trigger wires. That'll be easy to wire up two externally fused relays. I would even use the same resistor though it might be cheaper to buy a new one online somewhere in case you burn up the factory resistor (anyone know the specs to the OEM resistor?) I thought it was one wire running at two different voltages which makes for one trigger wire. If you don't care about running at dual speeds just wire your relay to the low trigger wire and bypass the resistor. The fan will always run at high at the low temp trigger threshold temp (84C).

FWIW, The electric dual stage *single* fan on my Chevelle would blow 30amp relays almost everytime ambient got over 90degs. I had to upgrade to a 40amp Bosch relay and it held. These fans draw a lot of power. I don't believe the 7amp draw myself - seems too little. Perhaps that doesn't take into account the spike at initial startup.
 
Last edited:
RYU said:
According to BrianK, It sounds like the circuit is controlled via two different trigger wires. That'll be easy to wire up two externally fused relays. I would even use the same resistor though it might be cheaper to buy a new one online somewhere in case you burn up the factory resistor (anyone know the specs to the OEM resistor?) I thought it was one wire running at two different voltages which makes for one trigger wire. If you don't care about running at dual speeds just wire your relay to the low trigger wire and bypass the resistor. The fan will always run at high at the low temp trigger threshold temp (84C).

FWIW, The electric dual stage *single* fan on my Chevelle would blow 30amp relays almost everytime ambient got over 90degs. I had to upgrade to a 40amp Bosch relay and it held. These fans draw a lot of power. I don't believe the 7amp draw myself - seems too little. Perhaps that doesn't take into account the spike at initial startup.
Click to expand...
The trigger wires are from the fan control unit to the relays, beyond that it is actually a switched ground. The fan receives power all the time but doesn't have a ground until it's supplied through the relays. But you can use them to trigger a different relay like you said. The resistor is listed as .6 ohm but i am unsure of the wattage. Just make sure the low relay doesn't step out when the high relay kicks in if that's the only one you use.


Mike
 
comtec said:
The trigger wires are from the fan control unit to the relays, beyond that it is actually a switched ground. The fan receives power all the time but doesn't have a ground until it's supplied through the relays. But you can use them to trigger a different relay like you said. The resistor is listed as .6 ohm but i am unsure of the wattage. Just make sure the low relay doesn't step out when the high relay kicks in if that's the only one you use.


Mike
Click to expand...

Excellent points. Didn't realize the low speed (-) trigger could cut off one the high trigger comes on. That would be annoying.
 
There are couple ways you can wire this. Just make sure if your putting the fans in the stock location you wire it as a puller fan.
 
I just bought a Masiv radiator. Thinking of getting dual spal fans. Any recommendation on which model to get?
Any advice on how to wire the fans? Do we need new and bigger batteries?
 

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