Quote:
Originally Posted by MDPotter
Not to hijack this thread, but I will be doing the same thing in the future on my 2004 Gen III and my dad's 2012 Gen IV is a similar setup. On my dad's we installed (2) relays - one for each fan and also the trinary switch and we thought we had it installed correct. He took it to a local shop that has installed a lot of VA units to have the system charged and they added a third relay which turns on the second fan whenever the compressor is engaged. It appears that the wire coming from the VA compressor is the signal for this third relay. So is the trinary switch even doing anything in this scenario? Fan 2 cycles a lot as the compressor is constantly cycling (dependent on where the temp inside the cab is set). It seems to me that the trinary switch should control the fan, not the the compressor.
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Most people run 3 relays so both fans kick on in when the ECM goes to the high fan or when the trinary pressure triggers it. They may have hooked it up to run off the compressor rather than trinary but that would be more cycling than using a trinary which measures the pressure and turns the fan on at a certain pressure. You could have just run a binary if the e-fans are wired directly to the compressor.