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I have a Lennox Conservator G8E furnace with Johnson Y79ABD-1 ignition control. More and more often now, when the thermostat calls for heat the ignition seems to go through it's spark/sense sequence and then shut down. Then of course the heat never comes on. Other times it operates normally. Do you have any explanation for this erratic behavior?

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  • bigblu Dec 03, 2008

    Thanks Joe. I received the same advice from HVACmechanic.com. You were both right. So far so good.

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You need to check the flame sensor and make sure it is putting out 4 to 6 microamps from the wire to ground

Posted on Nov 30, 2008

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Our Lennox Conservator G8E furnace goes through several ON-OFF cycles (we counted up to 10 clicks) before it stabilizes and stays ON. Once it's ON it works fine. - Any suggestions?


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I have the same issue with a G21Q4-5-100-1 model lennox. House drops 8 - 10 degrees. I have 3 thermostats and all react the same way. I was told by service tech that the Ignition Coontrol Module is bad and acting intermittanely. ???

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machtcl1@verizon.net

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