I've got a friend with a furnace that keeps blowing control boards. They go out about once a year. Anyone know where to get the schematic for this board? This is the 4th one replaced in his Heil furnace. I searched and all we find is people selling boards, no schematics. Thanks, Charlie Luke
honeywell furnace controller schematic ST9120U1003
Nov 06, 2008
3 Replies
A quick peek at a photo of the board shows that it uses SSR's, quite like the crap in my swimming pool system controller.
I temporarily solved the problem by wiring in a conventional electromechanical timer. When the "cool" season arrives I'm going to replace the SSR's with real relays.
...Jim Thompson
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I love to cook with wine Sometimes I even put it in the food
SSR's are indeed junk... and perhaps just wiring in some real relays will do the trick. If you still want the schematic, just get a tech to trace out the circuit and measure the component values... that what I do whenever I need a schematic and have a sample board.
Best regards,
Jean
Maybe they changed the board to SSR's. The site I looked at has a photo of the controller which shows regular electromechanical relays, so he'll have to examine his board to see which version he has.
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Ed
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