another short cycling question

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Old 12-11-13, 09:14 PM
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another short cycling question

Ducane gas furnace, just started short cycling a few days ago.
Excuse my ignorance with the right terms/descriptions etc. but here goes.
Blower come off and on...roughly 3 mins on...2 mins off...then repeat.
Combustion never turns off.
So the big flames will just suddenly turn off...then about 30 secs later the blower turns off. 90 secs later the big flames come back on, then 30 secs later the blower comes back on to start the cycle all over again.

Tried jacking up the thermostat, no difference.
Put the thermostat real low...the furnace appropriately completely shuts off.

Furnace is old school...no LEDS for diagnostics.

Thanks in advance!
 
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Old 12-11-13, 09:44 PM
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Welcome to the forums.

Do you have a FAN ON switch on your thermostat ?
If so..... turn it on and see if fan stays running.

Without a model number for your furnace I don't know what controls your blower fan. It could be time activated from a control board or there is a fan/limit control.

We need to determine if what controls the blower has a problem or the blower motor itself has a problem.
 
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Old 12-12-13, 07:13 AM
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as long as the stat calls the combustion runs filter?do you have an AC coil on top there?if so is it clean... supply fan squirrel cage rounds make sure they are clean no dust dirt build ups. trick... pop the fan access panel..slide it a little side ways then run the unit again does it run longer without tripping?...sounds like lack of air thru the unit...your tripping hi-temp when the main gas drops out...
 
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Old 12-12-13, 08:07 AM
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thanks for the reply sminker,
sorry but didn't understand most of what you're saying. my knowledge of furnaces is pretty much nothing.
the idea of tripping hi-temp, lack of air is what I was thinking as well.
got an hvac guy on his way now anyways....soon I hope...
i'll try moving the vilter out of the way like u said.
oh there here...will keep posted
 
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Old 12-12-13, 08:47 AM
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sorry model number is ducane cmpa100c4, which from my searches online...seems like they never made this model lol....no manuals anywhere so far
 
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Old 12-12-13, 08:21 PM
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Thanks also for the reply PJmax.
So repair guy came. There was some water in one of the condensate tubes. Drained it and now seems to be working well. Well, as well as it ever was.
 
 

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