Does anyone make a 3-relay fan controller?

[davepl]

I made one of these for my Camaro and it works great, but it's a lot of crimping and wiring and so on! I'm wondering if anyone makes one of these that I can buy off the shelf.

Basically its 3 relays so that you can set it up to run both fans in series on the low speed line (which is nice and quiet) and then in parallel when both wires go live.

[Steve Cole]

Hey Dave,

Derale makes a PWM controller that will turn the fans on a temperature that you select. I want to say the fans run at 60% initially (maybe less) and only increase as needed to cool to the set temp. I liked this because the fans put out 4000 CFM so I figured they would never run above 60% and be nice and quiet. Plus, they use soft start technology so they gradually spool up instead of 100% at once.

[weq92f]

I purchased one from local board member. It's the type where first signal runs in series ( half power or 6 volts ) and the second trigger/signal runs at full power or 12 volts.

gmachinz

He builds them to order so it takes a while to receive but it's a quality harness. I can shoot pics if you like.

-klb

[MARKDTN]

You might be able to do this with a Volvo relay. It is used to control a 2-speed fan. You could wire low speed to 1 fan and high speed to both (but you would have to add a big diode on the one that was used twice). Just Google "Volvo fan relay" and you can find wiring diagrams.

[davepl]

Originally Posted by weq92f

I purchased one from local board member. It's the type where first signal runs in series ( half power or 6 volts ) and the second trigger/signal runs at full power or 12 volts.

gmachinz

He builds them to order so it takes a while to receive but it's a quality harness. I can shoot pics if you like.

-klb

That's exactly what I want! If you have pics, please share!

[weq92f]

His off the shelf harness includes a thermostat set for triggering the fans at certain temperatures. Since I have a PCM under the hood ( EFI computer ) that has two fan triggers, all I needed was the harness that included the triggers ( negative/ground triggers ).

All leads are labeled.

Hth,

-klb

[87Skier]

Originally Posted by MARKDTN

You might be able to do this with a Volvo relay. It is used to control a 2-speed fan. You could wire low speed to 1 fan and high speed to both (but you would have to add a big diode on the one that was used twice). Just Google "Volvo fan relay" and you can find wiring diagrams.

The only issue with this is the volvo fans use two sets of coils in the fan (like windshield wipers) so they only take 12 volts to turn on. You would need another relay to switch the fans from series to parallel configuration.

I used the same wiring setup as the one posted above. I bought one of these fuse boxes https://www.waytekwire.com/products?pSearch=15303. It doesn't reduce the number of crimps you need to do, but it does make the installation a bit tidier.

[davepl]

Cool, I don't need the thermostats, just the ground-trigger lines.

Here's a pic of the last one I made, it's just a black box with two LEDs to indicate what power state the fans are in.

I also found this on Amazon, just looking at it now:
https://smile.amazon.com/Painless-30...30117+painless

[davepl]

I talked to Painless tech (which has an unlisted email!) and they confirmed that I can use the ECM to activate the two trigger lines. Just waiting now to ensure they run them in series/parallel rather than 1/2 fans.

[davepl]

Dang it, no luck:

"This will activate each fan individually according to the High and
Low commands coming from the ECM; see Figure 2. Both fans will activate when the A/C
compressor is activated."