I finally got around to picking up a low-temp switch from an '87-89 4.9L fuel rail & wiring it into the low-speed relay ground. It works - just as the thermostat opens, the fans come on.
I still have to find a hi-temp switch to trigger hi-speed, but I did add some wiring & switches to the dash so I can force the fans off, on hi (also with A/C), or leave them to run automatically.
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![heaterpipesensor.jpg I finally got around to picking up a low-temp switch from an '87-89 4.9L fuel rail & wiring it into the low-speed relay ground. It works - just as the thermostat opens, the fans come on.
I still have to find a hi-temp switch to trigger hi-speed, but I did add some wiring & switches to the dash so I can force the fans off, on hi (also with A/C), or leave them to run automatically.
[url=http://www.supermotors.net/vehicles/registry/media/575615][img]http://www.supermotors.net/getfile/575615/thumbnail/fancircuit.jpg[/img][/url]
See also:
[url=http://www.supermotors.net/vehicles/registry/media/894690][img]http://www.supermotors.net/getfile/894690/thumbnail/injectorblower.jpg[/img][/url] . [url=http://www.supermotors.net/registry/media/572490][img]http://www.supermotors.net/getfile/572490/thumbnail/heaterpipe.jpg[/img][/url] . [url=http://www.supermotors.net/registry/media/572778][img]http://www.supermotors.net/getfile/572778/thumbnail/heaterpipein.jpg[/img][/url] . [url=http://www.supermotors.net/vehicles/registry/media/894689][img]http://www.supermotors.net/getfile/894689/thumbnail/intakei6efi.jpg[/img][/url] . [url=http://www.supermotors.net/vehicles/registry/media/512250][img]http://www.supermotors.net/getfile/512250/thumbnail/heaterhose49l.jpg[/img][/url]](https://www.supermotors.net/getfile/624973/fullsize/heaterpipesensor.jpg)