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Rheem gas furnace pilot lights, but no burners or fan

Electric ignition gas pilot works, burners light faintly, but not fully, then die out. Pilot stays lit until I turn off thermostat. Last week, the furnace started acting up-would go through 4-5 cycles of coming on with burners and blower, then blower would go off for a minute or 2, while burners would stay lit. Then blower would come back on after another minute. After several cycles, everything would work. Now the burneres do not fully light, and of course the fan doesn't come on since there is no demand. Fan works fine when I switch it on. I took out the flame sensor to check it and it seems OK. No corrrosion build up, and it glows red hot. Could it be the flame sensor is shot? Furnace is 20 years old.

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If the burners do not fully ignite, the sensor will shut the furnace down. The lack of sufficient burner flame is a gas valve or gas pressure problem within the valve.
Replacing the gas valve with the original one may get you going. I surely suggest a professional service company for safety reasons and a thorough inspection. A 20 year old furnace is past it's normal life span.

Posted on Jan 06, 2009

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Heater is not igniting


see this causes and fix it. God bless you
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