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I have the LS3 crate engine with the GM stand alone wiring harness with fuse box and I don't know how to wire the fan wire coming out of the fuse box, thru the trinary switch to duel electrical fans. The temp sensor on the engine is wired into the fuse box and goes thru a relay and comes back out the fuse box labeled "fan''. I dont know how to wire it to the Vintage air trinary switch, split it to the two fans where the fan or fans come on when the engine is hot and/or when the a/c is on. Any wiring experts out there?

 

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Does the stand alone harness have one fan trigger or 2 like a factory vehicle? what is the amp draw of the fans (recomended fuse size?), does the stand alone harness supply just a trigger leg or is the fan relay built in, if it's a trigger leg is it positive or negative.

Assuming only one positive fan trigger from the computor and the fan set that comes with the CBR radiator I would run two 30 amp relays and two 30 amp breakers one for each fan, use the trigger legs from the computor and trinary switch to activate the relays and if your worried about back driving the computor from the trinary side add a diode to the computor trigger leg.

This way you would have both fans on with AC, and both fans on when coling is needed.

If you have a high and low trigger from the computor then you can run one fan at med temp and both fans for high temp and AC. This is how my wagon is wired with a two speed fan.

In my brothers car with an L33 and no AC the fans are staged with the stock computor. I don't believe the second fan has ever come on while driving even in stop and go traffic on a hot day it runs just under 180 deg with a stock thermostat.
 

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If the compressor cycles the switch is working, the question then is, is it cycling at the proper pressure? If the compressor never cycles that could indicate a problem with the system either in design or function.
 
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