Furnace Blower Fan Stays on

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  #1  
Old 01-08-16, 05:23 PM
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Furnace Blower Fan Stays on

OK so I replaced the limit switch and the circuit board already - the limit switch checks out fine and is not stuck open>
I also placed a wired between the two wires from the limit switch and sat there for about 5 minutes and fan did not shut off>
The only way to get the fan to shut off is to either kill power to the whole unit or to unplug the wire leading the the low side on the circuit board.
I am thinking I hae a faulty circuit board, but maybe not

This is a Carrier Model 58GP100-CA
 
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  #2  
Old 01-08-16, 05:32 PM
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FYI - i unplugged all wires except for the power, the transformer and the low side of the fan relay
all other wires are unplugged
Fan still stays on
 
  #3  
Old 01-08-16, 05:53 PM
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Did you check the fusible link? Do you have a spill switch on the vent pipe with a manual reset?

If you unplug any safeties it would create the same open circuit as a tripped safety. A volt meter is the best way to test for the cause.
 
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Old 01-08-16, 06:22 PM
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No manual spill switch - I see the fusible link but not sure how i could test it
 
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Old 01-08-16, 06:25 PM
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Well just thinking about it i turned the power switch on and put my leads from my tester one in front of link and one in back and it read 27+
 
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Old 01-08-16, 06:36 PM
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Sounds like an open fusible link.
 
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Old 01-08-16, 06:38 PM
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I tested the wired behind the link to the other post and got 27+ but if i put my lead in front of the link i get no reading
I also get no ohms if i test with it unplugged with leads in front and behind the link
 
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Old 01-08-16, 06:41 PM
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If it is an open fuse link - i think what caused it was that my relay switch was going off and on before and after the furnace would start and stop. This is why i replaced my circuit board in the first place - i am thinking that sometime in the night before i changed the circuit board the on and off of the fan cause some oer heating or the fan stopped all together and caused..
 
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