Heil furnace circulating fan stays on

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Old 04-11-14, 05:58 PM
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Heil furnace circulating fan stays on

model mf 12F1900A2
circulating fan stays on even when thermostat is removed, when I turn off switch at main panel fan goes off for awhile, then it will cycle on and off and then stay on. I replaced the control fan timer, didn't help. I removed all control wires to the control module, the fan still stays on.
 
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Old 04-12-14, 07:52 PM
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http://icpindexing.toddsit.com/docum...4201220501.pdf

That diagram looks alot like Carrier's.
What heat strip do you have installed in this unit?

Do you have a sequencer installed? They often cause this problem...
 
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Old 04-12-14, 09:08 PM
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it has a AMFK20DHB1 heating unit, no sequencer installed
 
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Old 04-13-14, 10:51 PM
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Looks like the blower is controlled strictly from the fan control board.

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Old 09-03-14, 08:22 AM
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I agree with the comment that fan is be controlled from the control board so if you’ve removed the board, how is the fan still getting a signal. Such situations usually demand reverse engineering, not the fan but the circuitry. It is important that you need to follow the control signal. You can use the multi-meter and see where the control signal is connected to. This will certainly clarify how your fan works.
 
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Old 09-03-14, 09:37 PM
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After turning off main switch at the furnace for about the fifth time, which was after I replaced the control module, the fan started to work properly. Thanks.
 
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