blower cycle


  #1  
Old 02-15-03, 09:18 PM
bob321
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blower cycle

I have a six year old bryant furnace mod/383kav048111agja
the burner ignites but goes out after only about ten seconds and befor the blower comes on. If I switch the fan setting at the thermostat from auto to fan the burner will ignite and stay on long enough for the blower to come on. Then I will switch the fan setting back to auto and the furnace will work normally for a few hours and then start the problem all over again.Any suggestions??
 
  #2  
Old 02-16-03, 05:02 AM
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Wow that is weird. The only way the blower should be able to stop the burner is if the plenum temp is at high limit. I don't think that is your case because there is no way the plenum could heat up in 10 seconds. You didn't say what the fuel was but I am assuming it is gas. Is the blower normally triggered by a temperature control or does your furnace have a main control board that controls the blower by time delay?
If a small dip in power occured at the time the blower was starting, it could cause a lockout. That could happen if the blower motor was going bad, or had a bad capacitor, but the blower works OK when switched on manually. I believe it is possible that the control board could be at fault.

Odd things like this are also caused occasionally by a bad electrical connection somewhere. Maybe a ground wire on a flame sensor.

Wait for more input on this one and please let us know when it is resolved because it doesn't fit into any category that makes it apparent what to look for and I want to know for the future.
 
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Old 02-16-03, 05:20 AM
H
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high limit?

It is feasable that the high limit is opening IF there was a hole in the heat exchanger and won't heat it bad enough if the fan runs...but to confirm its the high limit that is opening, you need to locate the high limit switch, put a meter across the terminals and see if it is opening.some have auto reset I assume yours does, if not...it's not going off on high limit. Is this gas?
 
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Old 02-16-03, 06:47 AM
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bob321:

Not sure if this applies to your furnace but here's some reading on intermittent ignition:

http://www.achrnews.com/CDA/ArticleInformation/features/BNP__Features__Item/0,1338,65283,00.html
 
  #5  
Old 02-17-03, 11:36 AM
bob321
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Talking blower cycle

the flame sensor was @ falt for my problem thank you for your help
 
 

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