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Fire chief fan limit switch problems

Beaver123

Beaver123

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Does anyone have any ideas why the blower is short cycling , I watch the fan limit switch n it doesn’t even run till it hits the off setting, I’m very confused n frustrated! Please help!
 
Capitalist

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Does anyone have any ideas why the blower is short cycling , I watch the fan limit switch n it doesn’t even run till it hits the off setting, I’m very confused n frustrated! Please help!
Dunno the ztove or motor... Does it have a run capacitor? Possibly bad?
 
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Beaver123

Beaver123

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Motor n capacitor seem good, I can watch the switch rotate to the on position but as the blower run it rotates back nowhere near the off position n it shuts off????? Don’t understand why
 
Capitalist

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Motor n capacitor seem good, I can watch the switch rotate to the on position but as the blower run it rotates back nowhere near the off position n it shuts off????? Don’t understand why
Sounds like possibly the motor has a thermal protection malfunction.
Wish I knew more
 
babybart

babybart

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What is a thermocouple reading on a wood furnace? The fan capacitor is a start capacitor not a run capitol, if it starts it's good. Your fan motor is bad, it is shutting off early on internal thermal overload.
 
Capitalist

Capitalist

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What is a thermocouple reading on a wood furnace? The fan capacitor is a start capacitor not a run capitol, if it starts it's good. Your fan motor is bad, it is shutting off early on internal thermal overload.
Its preset by the switch.

Its simply the cheapest possible fix and I would not chang a switch without doin it too.
 
Capitalist

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Fire chief does not build their own switch so its prob a honeywell which is testable with a multimeter but if it kicks on in the first place the multimeter may not see the issue unless the kickout is just hitting because the switch is defective.

Regardless you should be able to disconnect the blower and if the switch kicks off before the stop still then you can eliminate the motor as the issue.
 
babybart

babybart

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That is the fan limit. If he just jumps out the limit switch and runs the fan, that will tell. If the switch has a white knob on it, pull it out and the fan should run continuous and the switch is out of the equation. You should not need a fire for that. If the fan quits, motor. If the fan continues to run, switch.
 
babybart

babybart

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Sorry, just looked at a Fire Chief switch, made by Honeywell. Push the button for manual fan, pull the button for auto fan.
 
Mustang71

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Sounds like a bad fan limit or not enough heat to keep the limit closed. It's just a spring that expands as it heats up and turns the blower on and as it cools it contracts and turns the blower off. Do that 8 million times and they get weak. Mines a honeywell and half the time I just push the button in based on how the fire is burning. If its rolling secondarys then I turn it on so it doesnt short cycle. Just because the spot where the limit is isn't hot doesnt mean the spot where the air is coming out is not hot.
 
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