Best place for efan thermoswitch

[FerociousP]

Originally Posted by Pete_89T2

That's correct -the stock ECU (S5 T2 at least) uses the A/C switch to trigger the increase in idle speed. That's independent of the water temps. But I would caution using the existing auxillary e-fan wiring as-is to directly drive the Taurus e-fan, as that sucker will draw much more current than the stock aux. fan. What you could do is use the wiring up to the aux e-fan motor, and instead of having it power the motor, use it to energize a relay, which would in turn switch a circuit sized accordingly to supply current for your Taurus e-fan. At that point you can chuck the stock aux. e-fan as the Taurus fan will be doing its job, and handle regular cooling needs, provided you swap out the stock temp switch for the Summit one that trips at the lower temperature as you suggested a few posts ago. If it were me though, I'd look for a switch that trips below 200*, like 185~195*F.

Well, that would be using a relay to switch a relay... but whatever. And also, notice in the FSM that the thermostat doesn't even fully open until 203*. If normal operating temp is 190-195, then the fan would come on while you were driving down the road, which you don't want to happen. As long as the connections are in good shape I'd imagine the wiring to be satisfactory.

But... if the switch isn't even there then this all doesn't matter. Just trying to make the mod as simple as possible. FWIW, I still use the fan clutch on my current T2 and have had zero cooling issues. Is the minimal parasitic loss worth the hassle?? Not to me.