Lous69, thanks for the response. I have read thru your thread about PWM to control the fans several times and it seems like a very interesting way to go. I was trying to keep my control strategy a little simpler. If instead of going with PWM can I get the ECM to control my fans thru a low-speed/high speed control architecture driven by a function of the AC pressure and / or the engine coolant temp? If I understand what you are saying the trinary switch turns on the AC compressor with a signal from the VA controller, then the fans turn on or off as required driven by the GM AC pressure switches (low and high) or ECT with the appropriate ECM calibration.
I am still unclear about a few things.
1. Is it possible to get idle bump when the AC compressor turns on?
2. Is there a signal from the ECM to shut off the compressor at a specific rpm or do I still need the normally closed rpm window switch? Several friends do not have rpm protection in their LS installations and have exploded a couple of compressors, literally.
3. Is there a signal to the ECM, maybe from the electronic throttle pedal, that I can use to disable the compressor on WOT?
My research has indicated that I pretty much have to keep the AC compressor control separate from the ECM. So I am curious how you are handling compressor rpm protection and WOT compressor disable in your build with PWM?
Thanks for your help.
Bruce L
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