PWM for fans, will this work?
 

I am wanting to power and control my two Spal fans from my Holley HP ECU via a PWM controller (the Ford Fusion version) and have come up with a plan. I know this has been discussed at length in another post bout I would like to get some opinions as to whether or not this will work. Pictured below is a schematic I have hand drawn and a photo of what I have set up in the input/output of the ECU.

I don't see why not. If I had AC I would use CTS and AC pressure as well.

Andrew

Thank you. Larry

Larry,

I just looked at the schematic again, and I would add a 40amp breaker between the battery 12v+ and the fan controller.

Andrew

Ok, I will. Thanks for your help. Larry

Great time for this question, thanks for posting.

Why do you prefer the ford pwm over the Chevy? Is one that much better than the other?

To the best of my knowledge, they are identical. I avoided the "Corvette tax" by purchasing my Ford Fusion units new off eBay, so my motive in getting the Ford modules was cost.

That said, when I hooked mine up today, including the 40 amp breaker, as soon as I connected the ground wire to the PWM, the fans came on. This is with the cold engine not running and the key off. I cannot yet say it is the fault of the PWM module or a wiring error, more research is necessary.

I hope Andrewb70 will step in here. Larry

UPDATE!!! It works! After I fixed the wires I had inadvertently crossed, it works as advertised. My schematic is good. The fans came on as I had set them up in the input/output section of the ECU. I ran the A/C and it still maintained the prescribed temperature. My thanks to all who offered help and encouragement to me in this project. I will take it our for a freeway cruise soon to give it a real test.

For anyone that may want to do this in the future, do you have the part number for the controller you used?

The part number for the PWM controller I used is: FOMOCO 6E53-8C609-AA

the Corvette P/N that I have for the controller is: 10377609

These two controllers look identical except for the printing on them.

I suggest reading through this series of posts, there is a wealth of info there. It is a bit long but in my opinion worth it. There is info there for the connector and related items.

https://lateral-g.net/forums/showthread.php4?t=40215

I read through quite a bit of the other thread but didn't see this asked...

Is this method of controlling the fans better than using a fan module from one of the wiring or radiator companies?

Jeff-

I really cannot say whether it is better than an aftermarket controller. Better is subjective; this method requires an ECU, whereas most aftermarket controllers are stand alone. PWM or pulse width modulation, has the advantage of being able to run the cooling fan(s) only as much as they are needed and that can be programmed, as I did in my Holley HP ECU. I do believe there are some aftermarket PWM controllers out there. Many, if not most, new cars use PWM controllers because It is more fuel efficient as well as extending the life of the fan(s), not to mention quieter than having a fan roaring at high speed when it is not needed. Hopefully others will chime in as I am far from an expert. Larry

That basically covers it.

Andrew

Same topic, new issue. My A/C was not performing up to what I thought it should and since I am short of time I took it to a reliable A/C man. He checked everything over and discovered it was slightly over charged and took care of that. He also noticed the compressor laboring and decided to unplug the jack to my A/C transducer which is in my PWM circuit. Immediately the fans sped up and soon the A/C was performing as it should be. This is good, but I am trying to understand why the fans would go to full or near full RPM when the transducer was unplugged. I tried this at home with the same results. I can and will change some of the parameters in the input/output PWM page of my HP ECU to get the fans to come on sooner, but would like to understand why the above happened. Any input will be appreciated. Larry

Bringing this back up to the top, as I started playing with the ECU (Dominator) programming.

Larry, is it possible that the values for the transducer is a bit off? So the ECU is reading the pressure lower that it actually is?

I'm sure Larry will chime in, but as I recall, he ended up having some wiring issues, which I helped him resolve, and it's all working as it should now.

Andrew

Thanks Andrew. It would be nice to know what kind of wiring issues Larry was having.