lennox furnace not igniting


  #1  
Old 10-25-07, 07:36 PM
K
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lennox furnace not igniting

Its a Lennox m/n 80mgf2-60a-7 s/n 6397d 04704.

draft inducer fan starts but i do not get ignition. actually it lit just once out of dozens of tries but only briefly. now no go.

according to blinking light codes it says:
>watch guard pressure switch>>> pressure switch circuit open or has opened 5 times in single call for heat>broken circuit to pressure switch>pressure switch hose leaks or disconnected>check pressure at induced draft motor>pressure switch closed.

my question now is how to diagnos problem when i can't follow the diagram to these various possible trouble sites.
any suggestions?

thanks!
 
  #2  
Old 10-26-07, 04:54 AM
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Try removing the air tube from the furnace to the inducer and cleaning out the hole. It sometimes will get something in it causing the pressure switch to open.
 
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Old 10-26-07, 09:58 PM
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tube doesn't appear blocked

removed hose & only could probe the length of the nipple at hose connection on the inducer fan side. could that be the issue?
 
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Old 10-29-07, 07:06 PM
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problem solved

turned out the nipple was packed tight with rust & ash.
had to sacrifice a small drill bit but was able to ream out clog.
started right up! thanks for the direction in which to look.
 
 

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