Attaching two Fan Control Modules in parallel
Thread Starter
Racer
Joined: Jul 2000
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From: ID
Attaching two Fan Control Modules in parallel
I just bought a Dewitts shorty radiator/fan combo for my C6 with an A&A supercharger kit. I need to run the two 25A spal fans which would exceed the power specs for the OEM fan controller. I just happen to have an additional OEM fan controller. Can I attach the control signal wire to both fan control modules and use one for each fan? I have a great desire to keep the control of the fans under ECM control. Not knowing the electrical characteristics of the signal input (and ECM output), I don't know if splicing and running the line in parallel to two modules would work or not.
Burning Brakes
Joined: Jul 2016
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From: Treasure Island, Lake McQueeney, Tx
I also bought one of their radiators, with the Spal fans. Are you saying that I can't splice both fans into the fan controller? That sure isn't what I thought I was buying.
Race Director
Joined: Dec 2013
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I just bought a Dewitts shorty radiator/fan combo for my C6 with an A&A supercharger kit. I need to run the two 25A spal fans which would exceed the power specs for the OEM fan controller. I just happen to have an additional OEM fan controller. Can I attach the control signal wire to both fan control modules and use one for each fan? I have a great desire to keep the control of the fans under ECM control. Not knowing the electrical characteristics of the signal input (and ECM output), I don't know if splicing and running the line in parallel to two modules would work or not.
As for single OEM PWM to both fans, drawing too much through the PWM, and going to burn it up instead.
Note, some have gotten way with such, since the Dewitts fans draw less power, but only for street use with the fans only coming on once it a while. If your going to be running the motor hard, where the fans will be coming on all the time full blast, questionable how long the oem PWM is going to hold up running both fans. so in cases of street use, moving the PWM up and way from the heat, helps a lot.
Last edited by Dano523; Sep 7, 2018 at 08:11 PM.
Race Director
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But your a strip guy, while I'm a road course track guy, so two different worlds of just how long/high of motor temps, that we will run the fans full blast for isntead.
Le Mans Master
Joined: Apr 2011
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From: Montreal
St. Jude Donor '13
Originally Posted by Dano523
Maybe,
But your a strip guy, while I'm a road course track guy, so two different worlds of just how long/high of motor temps, that we will run the fans full blast for isntead.
But your a strip guy, while I'm a road course track guy, so two different worlds of just how long/high of motor temps, that we will run the fans full blast for isntead.
Race Director
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As I said, street use should not have a problem with the PWM burning up with the two Dewitts fans; short of say trying to hold the motor temp at 160* (fan table tweaks) with the fans maxed at full tilt every time the motor is running instead.
Le Mans Master
Joined: Apr 2011
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From: Montreal
St. Jude Donor '13
Originally Posted by Dano523
As I said, street use should not have a problem with the PWM burning up with the two Dewitts fans; short of say trying to hold the motor temp at 160* (fan table tweaks) with the fans maxed at full tilt every time the motor is running instead.
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Thread Starter
Racer
Joined: Jul 2000
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From: ID
realcanuk - you are running dual spal fans on the OEM fan controller with that kind of horse power? Maybe it'd be OK to try. Going from memory (which is a bit dicey these days) I was thinking the fuse on the fan was 40A and the two DeWitts spal fans were a total of 50A. I'm too lazy to go and look. That, combined with my melting connectors going to the controller worry me a bit.
If I had a circuit diagram for the ECM and the PWM fan controller I could figure it out, but with that being unlikely I'm concerned with overloading the PWM signal from the ECM.
Anyway, would be if DeWitts would weigh in. I've sent them two emails and haven't heard anything back. All I got from them was a radiator/fan combo with a catalog for their new radiators thrown in ?!?
If I had a circuit diagram for the ECM and the PWM fan controller I could figure it out, but with that being unlikely I'm concerned with overloading the PWM signal from the ECM.
Anyway, would be if DeWitts would weigh in. I've sent them two emails and haven't heard anything back. All I got from them was a radiator/fan combo with a catalog for their new radiators thrown in ?!?
Le Mans Master
Joined: Apr 2011
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From: Montreal
St. Jude Donor '13
Running dual spals with a Dewitt's rad. Stock controller and I'm pretty sure the stock fuse is 60 amps. The connector should be addressed so you don't have trouble but everything else should be fine.
My car makes 1000rwhp and the fans work plenty.
My car makes 1000rwhp and the fans work plenty.
Thread Starter
Racer
Joined: Jul 2000
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From: ID
Same here - I'm only running at 500RWHP with the A&A SC and you can hear the fans maxed out at any stop-light on a hot day with the AC on. Honestly, I think stop-and-go traffic uses the fans a lot more than any type of racing - though admittedly I've only done autocross and 1/4 mile. Even with my fan broken on a hot day (that wasn't a fun day) anything over about 35MPH would cool the engine down to about normal. But at a stoplight, the temp would quickly start getting dangerously high.
Burning Brakes
Joined: Jul 2016
Posts: 819
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From: Treasure Island, Lake McQueeney, Tx
Interesting stuff. I haven't got my new radiator and fan setup, yet. I'm not going to be installing it for a time. I just got a new fan assembly and module, under my GMEPP. When it runs out, I'm going to do bricks, snout and pulley. I thought I'd get a better radiator and fans, while they were on sale. I would like to know the best way to wire the fans up, when the time comes. I wish someone made a plug and play pigtail, for the Spal fans to the stock fan module, if that is indeed how I will be wiring it. Appreciate the information.
Team Owner
Joined: Nov 2007
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From: Gilbert AZ
My first suggestion would be return the spal fans and just run the OEM, as it cools better.
As for road racing with them, factory ecu turns the fans off past ~40 or so (can't remember exact number) so as soon as you the track, unless it is a road course where you are constantly under 40, the fans are just there for a ride.
As for road racing with them, factory ecu turns the fans off past ~40 or so (can't remember exact number) so as soon as you the track, unless it is a road course where you are constantly under 40, the fans are just there for a ride.
Thread Starter
Racer
Joined: Jul 2000
Posts: 492
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From: ID
My first suggestion would be return the spal fans and just run the OEM, as it cools better.
As for road racing with them, factory ecu turns the fans off past ~40 or so (can't remember exact number) so as soon as you the track, unless it is a road course where you are constantly under 40, the fans are just there for a ride.
As for road racing with them, factory ecu turns the fans off past ~40 or so (can't remember exact number) so as soon as you the track, unless it is a road course where you are constantly under 40, the fans are just there for a ride.
Team Owner
Joined: Nov 2007
Posts: 24,035
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From: Gilbert AZ
What Jody said. Cheaper, easier to just lower the mounts on the radiator cradle, than kill the cool capability, and spend a ton of money doing it. If you still want a dewitts, because they are nice radiators, run the full size one.
Safety Car
Joined: May 2006
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From: Potomac MD
On the fans - if you are running the two - 25 amp fans that Prospeed (or something like that) uses I think you are right to do the dual controller. If you are talking about the plastic shroud dual 11 inch fan set up those fans each draw about 16 amps (the kit everyone sells) and I think that is what people are thinking you may have and people have not had problems with. Big difference in 32 amps versus 50 amps. I think the factory fans draws like 35 amps or so depending if you have it turned on all the way.
Race Director
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