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Lennox G20 ignition clicks but furnace won't fire up. Intermittent

nid15
nid15 Member Posts: 1
in Gas Heating
Hi,

We have a 25+ years old lennox G20Q4-SE furnace with Robertshaw ignition. It works well most of the time but once a day or other day, we will have cold air coming from vents and when I go down to check, I can hear the ignition clicking. I would turn off the power switch and turn back on. Sometimes it would start working the very first time and sometime I would be sitting there doing on/off for a long time before it works. When it works. I barely hear 1 click of the ignition. 
I know it's old and needs to be replaced etc. I just got the service done last week. The guy cleaned it, adjusted the gap etc.and told me the flame is perfect and the system was nicely maintained.  He is coming back today to check.

Thanks in advance.


Comments

  • saxman
    saxman Member Posts: 2
    did you ever find out what the issue was? I have something similar on my G20 as well
  • HomerJSmith
    HomerJSmith Member Posts: 2,635
    edited December 2023
    Round up the usual suspects. Check the large orange ignition wire for a break in the insulation from the ignition module to the spark igniter. You may see a black spot on the insulation where it rests against the metal cabinet indicating that the wire is shorting to the cabinet. Move the wire around and see if that helps.

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