Flame comes on for 2 secs then goes out

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Old 03-19-09, 03:15 PM
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Red face Flame comes on for 2 secs then goes out

I have just replaced the ignition control box on Trane XL80 furnace which is 18 year old. When thermostat is set higher, the ignitor glows, the flame comes on for a couple of seconds then goes out. I have checked the blower by itself (without heat and it runs fine). Is there a flame sensor on this unit that senses the presence of flame before turning the blower on? If yes, then could it be that the flame sensor has gone bad. Where is it located in the furnace. Thanks much for your help.
 
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Old 03-19-09, 03:48 PM
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The symptoms you describe could well be a flame sensor that needs to be cleaned of accumulated oxides. The flame sensor is typically on the opposite side of the furnace from the hot surface ignitor which glows to light the gas. It's usually a small rod sticking up into the flames with a single wire coming off the bottom and plugging into the ignition control module.

Removing the flame sensor and cleaning it with a wire brush would be worth trying.
 
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Old 03-19-09, 04:28 PM
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flame sensor clean it with steel wool
 
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Old 03-20-09, 01:13 PM
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Smile Problem Fixed !!

Thanks Seattle Pioneer and hgihvac for your responses. Last night when I went home, I checked the connection of the Flame sensor to the Ignition Control Module. Apparently, I did not connect it properly when I replaced the unit. It pulled out too easily and was not making an electrical connection. I reseated it properly, turned the unit on and it worked beautifully !!
 
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