Dual Spal Fans issue

[TERMN8OR]

I've got the PRC Dual Spal fan set up. I wired it up using the Spal dual harness setup.
It was working great for a few months, but now both fan intermittently turn on and off. I checked all the wiring, grounds etc and everything seems good.

I'm thinking the problem may be my alternator is not putting out enough juice. I believe it's only 60amp.
I'm running an electric fuel pump, and both fans at once.
Any other ideas ?

[Yelcamino]

Try the Spal fan controller (http://www.spal-usa.com/fans/automated/accessories/fanpwm.html). It only runs one fan until the engine temp requires two; as soon as the temp comes down the second fan shuts off and the primary fan will cycle as needed.

I have one on my Chevelle and it works great!

[TERMN8OR]

I know the controller is a good option, but without it the fan's shouldn't be going on and off. I wondering if they are drawing too much power and my alternator can't keep up. When I disconnect one of the fans and run them one at a time it seems to work fine.

[dhutton]

What gauge wire did you use?

[TERMN8OR]

I used Spal's dual harness that came with the unit. Not sure what gauge wire but I assume it's correct. It's the harness in the link below, except it's a dual harness

http://www.spalusa.com/store/main.aspx?p=itemdetail&item=185FH

[Yelcamino]

Where is your main power coming from? I have mine right on the alternator, which is a 120 amp, so as you stated in your OP, the alternator might not be able to handle the load.

[TERMN8OR]

Main power is coming off an accesory block. Does anyone know how many amp's the fans pull each ?

[prostreet69camaro]

Usually 20 to 25 amps. They recommend a 30 amp fuse for each one.

[TERMN8OR]

So around 40 amps for both.. Do you think that this is too much for my 60 AMP Alt ? I also have an electric fuel pump running. The fans are fine when only one is running.

[TERMN8OR]

So I just installed a new 140 Amp Alternator. I'm still having the same issue. I also installed a 185 degree sending unit for one of the fans. Once that second fan kicks on, both fans will turn off within 20 seconds.
I went over the grounds again, and everything looks good.
I'm at a loss. Anyone have any other suggestions ?

[dhutton]

So I just installed a new 140 Amp Alternator. I'm still having the same issue. I also installed a 185 degree sending unit for one of the fans. Once that second fan kicks on, both fans will turn off within 20 seconds.
I went over the grounds again, and everything looks good.
I'm at a loss. Anyone have any other suggestions ?

Could you post a diagram of how you have this wired? Probably a stupid question, but what is the coolant temperature when the fans turn off? Do they turn back on after a while or do they stay off while the coolant temperature rises?

[TERMN8OR]

I have one fan that is on constant. It comes on when the ignition is on. The other fan is hooked up to a 185 Degree sender that is installed into my intake manifold.

I have it wired as follow. There is a 30 amp reley on each fan, and a 15 amp fuse on each.
Both releys are tied together with a constant hot and an ignition hot. The constant Hot wire is attached to a block that is installed in the car. Along with the fans, the block also powers my electric fuel pump. ( I'm wondering if there is too much of a draw off this block). Both fans are also ground to the chassis. I tried to also ground them to the battery, but it didn't change anything.
As far as them going on, after the temp hits around 185 the second fan will turn on. They will both run for about 10 seconds or so and then both fans will shut off. Both will then click on and off every 10 to 15 seconds or so.

Wondering if I should hook up the constant hot directly to the battery.
I'll try and post a diaragram.

[TERMN8OR]

Here is the wiring diagram that I followed. I don't have the toggle switch hooked up.

[dhutton]

I think that junction block is some kind of resettable breaker or it is fed by one. You are exceeding it's current rating. Try taking the fan power directly from the battery.

[Taman]

60 amp alternator is pretty weak. You can get a 100 amp unit at Auto Zone for $30. Initial start up for the fans is killing your current. Add an ignition, fuel pump, stereo and headlights and forget it.

[jon72vega]

The OP has installed a 140 amp alternator since he started this thread.

[MrQuick]

I have one fan that is on constant. It comes on when the ignition is on. The other fan is hooked up to a 185 Degree sender that is installed into my intake manifold.

I have it wired as follow. There is a 30 amp reley on each fan, {and a 15 amp fuse on each.}
Both releys are tied together with a constant hot and an ignition hot. The constant Hot wire is attached to a block that is installed in the car. Along with the fans, the block also powers my electric fuel pump. ( I'm wondering if there is too much of a draw off this block). Both fans are also ground to the chassis. I tried to also ground them to the battery, but it didn't change anything.
As far as them going on, after the temp hits around 185 the second fan will turn on. They will both run for about 10 seconds or so and then both fans will shut off. Both will then click on and off every 10 to 15 seconds or so.

Wondering if I should hook up the constant hot directly to the battery.
I'll try and post a diaragram.

is that correct? should be 30.

On top of having a faulty Bat+ feed you also may have an overheating relay. That junction comes off of a fusable link.

Vince

[66zz430]

I think that junction block is some kind of resettable breaker or it is fed by one. You are exceeding it's current rating. Try taking the fan power directly from the battery.

2X this.
I run dual fans with the same wiring but running direct from the battery with no problems.

[TERMN8OR]

The fuses are 30 amp. Thought they were 15.
I'm going to run a line from the battery today. I'll let you know if it works.

[TERMN8OR]

problem solved. I got rid of the junction box and went to a direct battery feed. Works fine now.

[H2Ogbodies]

For long drives, I would suggest against running your fans off the battery-the constant surge of the on/off cyclign every 15 seconds is not gonna keep a good charge on that battery. The remote voltage sensing has a hard time trying to maintain system voltage when things are powered off the battery. You should run your main power leads from the alt. charging post via a remote common power junction that is not re-settable. Batteries need to store voltage/power, not supply it.

[ModernMuseum]

Here is the wiring diagram that I followed. I don't have the toggle switch hooked up.


Probably a long shot, but does anyone have the second page of this wiring diagram shown here (the pictorial with the connection to the trinary switch)? I've scoured the net and can't seem to find it (quoted from the previous page)

202522

[csouth]

Do a Google image search on Trinary Switch Wiring. Vintage Air has one out there. I'm not near a PC, but I just pulled it up....

[ModernMuseum]

I ended up calling SPAL and they sent me a scan, and I added some color to it.

Any idea what the little yellow boxes are supposed to be (near the fans) in the previous pic?

https://static1.pt-content.com/images/pt/2022/09/pkGxdCys_o-1.png (https://imgbox.com/pkGxdCys)

[CarlC]

Those are likely the disconnect/connect plugs.