Single-Speed Cooling Fan Circuit only allows the fans to run when the engine is running (because it's powered by the fuel pump relay), but gives the driver control (OFF) for water crossings or (ON) in case the temperature switch fails.
For a stock temperature switch, look at the '87-89 F150 4.9L injector blower switch:
For dual 15A fan motors, upgrade the 20A fuse & its wiring to 40A.
For carb, splice the 3A fuse into any RUN circuit, like the ignition module or voltage regulator.
For more-complex 2-speed circuits, see the NEXT several diagrams...
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:
![fancircuita.jpg Single-Speed Cooling Fan Circuit only allows the fans to run when the engine is running (because it's powered by the fuel pump relay), but gives the driver control (OFF) for water crossings or (ON) in case the temperature switch fails.
For a stock temperature switch, look at the '87-89 F150 4.9L injector blower switch:
[url=http://www.supermotors.net/registry/media/624973][img]http://www.supermotors.net/getfile/624973/thumbnail/heaterpipesensor.jpg[/img][/url]
For dual 15A fan motors, upgrade the 20A fuse & its wiring to 40A.
For carb, splice the 3A fuse into any RUN circuit, like the ignition module or voltage regulator.
For more-complex 2-speed circuits, see the NEXT several diagrams...
See also:
[url=http://www.supermotors.net/registry/media/849725][img]http://www.supermotors.net/getfile/849725/thumbnail/fusesblades.jpg[/img][/url] . [url=http://www.supermotors.net/registry/media/830776][img]http://www.supermotors.net/getfile/830776/thumbnail/fusiblelinkrepair.jpg[/img][/url] . [url=http://www.supermotors.net/registry/media/832986][img]http://www.supermotors.net/getfile/832986/thumbnail/bulbsfuseswire.jpg[/img][/url]
https://www.fleet.ford.com/truckbbas/non-html/1997/c37_39_p.pdf
This diagram was created from this set of symbols using MSPaint:
[url=http://www.supermotors.net/registry/media/858661][img]http://www.supermotors.net/getfile/858661/thumbnail/wiringsymbols.gif[/img][/url]](https://www.supermotors.net/getfile/642421/fullsize/fancircuita.jpg)