trane xl 80 2 stage: locked out


  #1  
Old 05-12-10, 12:59 PM
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trane xl 80 2 stage: locked out

hi all,
I have a trane xl 80 2 stage furnace. It keeps locking out after a few calls for heat. Diagnostic code blinks twice. The ingitor glows brightly. I have cleaned the heat sensor. After cleaning the sensor, it did fire up a few times, but when I woke up in the morning, the house was cold and the funace was again blowing cold air and locked out. Any help would be appreciated.

Regards,
RM.
 
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Old 05-12-10, 04:13 PM
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The blower would come on but there were no flames? I am not sure what you are describing. Why not hit the off switch. wait a minute. Turn it back on as describe what happens.
 
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Old 05-13-10, 04:31 AM
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I have turned the unit off at the switch. When I turn it back on, the ignitor glows, the flames come on, the blower comes on, everything seems fine. Then the flames go out. and the blower is blowing cold air. When the unit tries to call for heat, it won't fire back up.. it locks out. The ignitor glows, but no flames. I have cleaned the heat sensor... wondering what could be wrong?
 
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Old 05-13-10, 11:07 AM
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When my furnace does that it is because:

1) The blower motor overheated, due to: Squirrel cage being fouled, or airflow in being blocked by for example a fouled filter. Your furnace may have a second blower for cold air. If it is an older unit the electric motor may have oil ports, 3 in one BLUE LABEL specifically for electric motors. The blower motor sensor trips the relay to the whole unit and shuts it down permanently.

2) Exhaust may be blocked from escaping due to blocked chimney. CO heat sensor tripped, and tripped the master relay. My guess is there is a way to feel air being sucked out of the furnace into the flue to the chimney. On my furnace I can wet the back of my wrist, stick it under the flue and feel cold air being drawn into it. Removing the flue and inspecting the chimney with a mirror would say for sure. Be careful as the connection to the chimney may be more fragile than you thing.

At first I thought the sensor was broken but a very honest supply store clerk at H & L Heating Supply Inc Brooklyn, NY tested it and said it was fine.

I would advise searching the net for advice, I did and found much useful wisdom for real pros.

Note amateur DIY may be tempting but there is much that you can screw up, losing tiny screws or forgeting where they go. Stripping a screw is easy on sheet metal construction.

The above is the sum total of my gas furnace knowledge.
 
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Old 05-13-10, 06:58 PM
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Originally Posted by geo8rge
I would advise searching the net for advice, I did and found much useful wisdom for real pros.
Some of us who respond to posters on this forum actually diagnose and successfully fix furnaces for a living.

mercdr,

is it pretty symptomatic for the flamne to go out after a certain time period about every time this does it? How long does the flame stay on for before the flame goes out? Does the inducer fan(which is the fan that exhausts the gas to the outside of the house) continue to run when the flame shuts off? - or does that also turn off?
 
 

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