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
Quote:
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
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