PWM cooling fan(s) control using ECM

[andrewb70]

Originally Posted by dontlifttoshift

Thanks! I think I will replace the LS1 F body fans I have with that. I kind of like the half shroud, half open design, better than the full shroud.

Donny,

I don't hate the open design. Once a car is moving you want as much air as possible to just flow through. I wish the C6 radiator didn't have that funky angles upper hose. I would just use it in the Cougar and this fan mounts right to the radiator itself.



Anyone have any creative ideas how to mount this thing?

Andrew

[carbuff]

Originally Posted by andrewb70

Anyone have any creative ideas how to mount this thing?

I don't recall, do you already have your radiator? If not, can you have the mounts built in place on the end canisters just like the picture?

[samckitt]

Originally Posted by andrewb70

Donny,

I don't hate the open design. Once a car is moving you want as much air as possible to just flow through. I wish the C6 radiator didn't have that funky angles upper hose. I would just use it in the Cougar and this fan mounts right to the radiator itself.



Anyone have any creative ideas how to mount this thing?

Andrew

What is this picture of the fan mounted from? Any close shots of the mount points?

[samckitt]

I went to the junk yard yesterday & found a couple modules with connectors on fans that were busted. One of the connector bodies has a little damage to it, but still seals out the weather.

Who wants one?

[130fe]

PM sent Scot.

[Terrydmorgan]

I'm new to this forum, but I've been working on a couple pro-touring type Camaros for about 6 years. I'm on Pro-touring.com, but I haven't been active on this site, just lurking. I really appreciate the effort that went into this thread. This is an elegant implementation of a PWM controller for the cooling fans. I've ordered all the necessary items and will have mine hooked up soon too. Thanks for all the info.

I'm wondering if we could extend this solution to get rid of the binary switch in a Vintage Air system and let the ECM control the Sandeen compressor too. As I understand it, the function of the binary switch is to protect the compressor. That is, if the AC pressure is too high, the binary switch interrupts electric power from being delivered to the compressor clutch. Likewise, the binary switch will also turn off electric power to the AC clutch if AC pressure is too low. It seems logical that GM would implement a similar safety feature in their cars. And, since the AC pressure sensor is coupled to the ECM, it would seem likely that this binary type safety feature would be implemented in the ECM. Thus, I'd expect that there's a software routine in the ECM that uses high or low AC pressure to turn off the AC compressor clutch, and we might be able to modify this routine to use pressures that correspond to the Sandeen compressor instead of a production compressor. Moreover, I'd heard that GM's ECMs turn off the AC clutch if WOT or high RPMs is detected. The same routine may handle these functions too. These would be features I'd like to have implemented in my cars too.
I'm not highly experienced with ECMs and their software or with AC systems. I'm just trying to think about this logically. So, feel free to tell me I'm all wet, and/or point me to some materials that would help move this matter forward.

[mikels]

Originally Posted by Terrydmorgan

I'm new to this forum, but I've been working on a couple pro-touring type Camaros for about 6 years. I'm on Pro-touring.com, but I haven't been active on this site, just lurking. I really appreciate the effort that went into this thread. This is an elegant implementation of a PWM controller for the cooling fans. I've ordered all the necessary items and will have mine hooked up soon too. Thanks for all the info.

I'm wondering if we could extend this solution to get rid of the binary switch in a Vintage Air system and let the ECM control the Sandeen compressor too. As I understand it, the function of the binary switch is to protect the compressor. That is, if the AC pressure is too high, the binary switch interrupts electric power from being delivered to the compressor clutch. Likewise, the binary switch will also turn off electric power to the AC clutch if AC pressure is too low. It seems logical that GM would implement a similar safety feature in their cars. And, since the AC pressure sensor is coupled to the ECM, it would seem likely that this binary type safety feature would be implemented in the ECM. Thus, I'd expect that there's a software routine in the ECM that uses high or low AC pressure to turn off the AC compressor clutch, and we might be able to modify this routine to use pressures that correspond to the Sandeen compressor instead of a production compressor. Moreover, I'd heard that GM's ECMs turn off the AC clutch if WOT or high RPMs is detected. The same routine may handle these functions too. These would be features I'd like to have implemented in my cars too.
I'm not highly experienced with ECMs and their software or with AC systems. I'm just trying to think about this logically. So, feel free to tell me I'm all wet, and/or point me to some materials that would help move this matter forward.

You are correct in that GM ECM's do control AC compressor - however - GM ECM's receive AC compressor request signal over LAN from BCM (no discrete AC compressor request input directly to ECM).

So best solution I've come up with is AC pressure sensor into ECM to control fan output based on AC pressure - then use Vintage Air trinary switch to control compressor.

At least this way you can control fan output from coolant temp, oil temp, trans temp, intake air temp and AC pressure.

Dave

[Terrydmorgan]

Dave,
Thanks for the reply. I see, so if the ECM never receives an AC compressor request, then I assume the output signal from the ECM remains high all the time (i.e., the output is never pulled low by a real AC compressor request from the BCM)? Is there a way to permanently tie the AC compressor input request to simulate a constant request for AC from the BCM?
Terry

Originally Posted by mikels

You are correct in that GM ECM's do control AC compressor - however - GM ECM's receive AC compressor request signal over LAN from BCM (no discrete AC compressor request input directly to ECM).

So best solution I've come up with is AC pressure sensor into ECM to control fan output based on AC pressure - then use Vintage Air trinary switch to control compressor.

At least this way you can control fan output from coolant temp, oil temp, trans temp, intake air temp and AC pressure.

Dave

[samckitt]

Originally Posted by andrewb70

Donny,

I don't hate the open design. Once a car is moving you want as much air as possible to just flow through. I wish the C6 radiator didn't have that funky angles upper hose. I would just use it in the Cougar and this fan mounts right to the radiator itself.



Anyone have any creative ideas how to mount this thing?

Andrew

For others looking to mount the Corvette C6 fan on an aluminum radiator. I found that C&R Racing makes a OEM style aluminum radiator for Corvettes. I contacted them & was able to purchase the little mount tabs from them.

[andrewb70]

Scot,

Good stuff. So you ordered 2 of each? I gather each one of the part number is specific to the 4 corners...right?

Andrew