Intermintent Furnace Problems


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Old 03-12-14, 09:09 AM
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Intermintent Furnace Problems

My son has a Lennox Mod. G23Q2-50-4 natural gas furnace. Intermittently he will get up in the AM with it not working. He will shut the power off for a couple minutes and it will restart. He replaced the flame sensor but is still having problems. Any ideas where to start from there? THX.
 
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Old 03-12-14, 10:45 AM
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There is a control board in that unit but the LED on it has limited diagnostic capabilities.

You furnace uses a spark module to light a pilot. Once the pilot is lit and acknowledged.... the main burner will light. That pilot assembly is critical for proper operation. More than likely the pilot orifice is partially clogged. The pilot flame must be big and blue not orange and weak.

The following link is the manual for your furnace.
Lennox/documents/G23 SERVICE.pdf
 
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Old 03-12-14, 12:01 PM
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Thanks for the link PJ. It is a big help.
 
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Old 03-12-14, 12:17 PM
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Sometimes it's easier to read and diagnose a problem directly from a service manual but if you have questions.... be sure to post them.
 
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Old 03-14-14, 05:29 AM
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After doing a little research online, the problem stems from a loose connection or solder joint with the ignition control module. (Johnson Controls G776RGD-11). A little wiggle with the ground wire seems to rectify the problem. We're going to monitor at this point, but probably change out the control. Cost, anywhere from $100.00 to $150.00 (Johnstone Supply) depending on the brand. THX
 
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Old 03-14-14, 07:16 AM
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I had the same problem on another thread on this board. Turned out to be the same thing, loose connection that seems like it's in the module itself.
 
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Old 03-14-14, 12:53 PM
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The quality and reliability of any electronic component always comes down to the soldering quality.
 
 

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