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York Unit Running But No Heat

AardvarkAardvark Member Posts: 6
I have a York Model # G8C07512MUB11A. The heater seemed to be coming on but was blowing cold air. I checked the circuit breaker, thermostat settings and batteries -all good. Then went to the attic. I took the front panel off (no sight-glass) and re-started it. The igniter came on glowing orange but the burners never lit off. This cycled about 3 times and then I saw indicator on the circuit board flash 7 times indicating "IGNITION LOCKOUT DUE TO RETRIES." I had just replaced the air filters 2 days ago so, assumed that was not a problem. I took the flame sensor out and cleaned it since I had never done that. I saw that a mud dauber had started a nest in one of the burner tubes and cleaned that out. Tried again but still, no joy. The wiring all looks good and I didn't see any indications of water or condensate anywhere. Any ideas? I'm open to any suggestions. FYI, I'm a retired Marine, Jack of all Trades, and PHD (Poor, Hungry, and Driven). So, if you can point me in the right direction, I think I can fix this thing.


  • Jamie HallJamie Hall Member Posts: 12,706
    Improvise, Adapt, Overcome good buddy. Natural gas? LP? If LP, do any other LP fired appliances run? Gas pressure low or gas valve not opening?
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • icy78icy78 Member Posts: 345
    More mud dauber detritus. Or spider. Can you feel the gas valve click?
    If theres a mud dauber nest, then this is first time firing the furnace in a while?
  • AardvarkAardvark Member Posts: 6
    @Jamie Hall It's Natural gas - only other appliances are water heater and fireplace. Both of those are working as advertised.

    @icy78 I'm in NC so, yeah, long summers and usually mild weather but we just had that fluke winter storm last month and it work great then. So, this was an unexpected problem. I didn't feel the gas valve at all - I'll check that now.
  • AardvarkAardvark Member Posts: 6
    @icy78 Tried it again. I didn't feel the gas valve click but, then again, it's close to the blower motor and there's so much vibration...not sure if you could notice anyway.
  • icy78icy78 Member Posts: 345
    > @Aardvark said:
    > @icy78 Tried it again. I didn't feel the gas valve click but, then again, it's close to the blower motor and there's so much vibration...not sure if you could notice anyway.

    There shouldnt be vibration. Slight bit only. Is the ignitor glow bright orange?
  • AardvarkAardvark Member Posts: 6
    @icy78 Yes sir. The igniter is glowing bright orange.
  • HVACNUTHVACNUT Member Posts: 3,272
    With the igniter glowing and the diagnostic code, all safeties are closed allowing a trial for ignition. If there were a different diagnostic code like open pressure switch or open limit, it wouldn't get as far as trial for ignition.
    Have you checked the wiring to the gas valve? All tight?
    Unfortunately you'll need a meter to see if theres 24v at the gas valve at the time of ignition.
    You said the furnace is in the attic. Any chance it's a 2 story home and you have heat on the first floor?
  • AardvarkAardvark Member Posts: 6
    @HVACNUT Fortunately, I do have a multi-meter. Even more fortunately, as I was checking the voltages, the system fired up and I now have heat! Maybe a little oxidation on the terminals - who knows? - but good to go for a few hours now. Thanks everyone! I appreciate all your help.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 6,935

    As the furnace is in an attic some corrosion on the wiring terminals is sometime a little more likely do to condensation. When the weather warms up you could rework the wiring connections
  • AardvarkAardvark Member Posts: 6
    @EBEBRATT-Ed Understood, that's a good idea. I will certainly do that. Being in the attic - out of sight and out of mind - it's hard to realize or remember how dirty things can get. (Or that mud daubers and spiders can make their home there!) LOL! G'nite all - think I might get a good rest tonight. :)
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