A more-complex variation of the 2-speed e-fan circuit; this one includes a relay that allows high speed when the A/C is running. Note that the OFF position on the dash switch does not affect the high-speed relay, so it's idiot-proof. Even if the dash switch is left OFF, the fans can still come on if the engine goes above the high-temperature switch threshhold, or if A/C is on. The fans cannot be truely disabled if the engine is close to overheating, even with the key OFF. To totally kill the fans, the 40A fuse can be pulled.
For other configurations, see:
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For carb, splice the 1A fuse into any RUN circuit, like the ignition module or voltage regulator.
See also:
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https://www.fleet.ford.com/truckbbas/non-html/1997/c37_39_p.pdfThis diagram was created from this set of symbols using MSPaint:
