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Bryant Furnace Ignition Lockout

aelb771
aelb771 Member Posts: 7
in Gas Heating
Hello everyone,
I'm a homeowner trying to troubleshoot my furnace and hoping someone can help. I have a Bryant 352aav that's about 15 years old. I'm having my basement finished, and unfortunately I didn't turn off the furnace while they were finishing the drywall (I know, very stupid of me). A lot of drywall dust got into the filter which I replaced. I also used compressed air to clean out the inducer motor, and the inside of the furnace. Then one day last week it stopped working and I'm now getting an ignition lockout code (14).
I can see the ignitor turning bright orange, and all three burners turning on, but then they shut off after a few seconds. I tried cleaning and then replacing the flame sensor and it made no difference. The vent pipes outdoors appear to be free of any obstructions. The condensate pump is working. I would assume that the ignitor and burners are working because there is a flame, but maybe I'm wrong? I tried to link a short video of whats occurring.

https://youtu.be/T56JvfDzMjM

I have a multimeter, so could check for basic measurements if you guys provide instructions.

Thank you so much for any help. I realize this is entirely my fault for not shutting off the furnace, but I'm just hoping I can avoid replacing the furnace.

Comments

  • HVACNUT
    HVACNUT Member Posts: 5,998
    Last line on code 34.
    Check/secure all grounds. 
    Hard to tell from the video but it sounds like the flames are pulsating. 
    You need a manometer to check lockup and manifold gas pressures.


  • JUGHNE
    JUGHNE Member Posts: 11,180
    The flame sensor is only half of that electric circuit.
    The pilot hood and ground system is the other half.
    If the hood is all craped up it may not respond as it should.

    Does the flame plusate like that if you have the burner cover back on?
  • aelb771
    aelb771 Member Posts: 7
    Thank you for the suggestion. They are pulsating, but I believe that goes away when I have the cover installed on the burner box. 
    I did check the green/white wires and they appear to be attached securely. 

    It sounds like I may have to call an hvac professional for those lockup/manifold pressures. 
  • aelb771
    aelb771 Member Posts: 7
    JUGHNE said:
    The flame sensor is only half of that electric circuit. The pilot hood and ground system is the other half. If the hood is all craped up it may not respond as it should. Does the flame plusate like that if you have the burner cover back on?
    Sorry for the stupid question, what do you mean by pilot hood? 
  • JUGHNE
    JUGHNE Member Posts: 11,180
    I should say if you have a pilot light. There would be a 1/4" aluminun tubing from the gas valve to the pilot burner.

    Perhaps this is direct burner ignition.
    But the part of the flame sensor that is close to the burner (or pilot if you have one), that metal must be clean also.
  • aelb771
    aelb771 Member Posts: 7
    Got it, it’s a direct burner ignition. But I will double check the metal close to the flame sensor as soon as I get home from work. 
  • aelb771
    aelb771 Member Posts: 7
    edited January 2022
    I cleaned out the area near the flame sensor as best I could and it still isn’t working. 
    Is it possible that the drywall dust caused a short circuit on the control board, and that it needs to be replaced?
  • HVACNUT
    HVACNUT Member Posts: 5,998
    aelb771 said:
    I cleaned out the area near the flame sensor as best I could and it still isn’t working. 
    Is it possible that the drywall dust caused a short circuit on the control board, and that it needs to be replaced?
    I doubt it but let's see what the tech finds.
    Natural or LP gas?
  • aelb771
    aelb771 Member Posts: 7
    Natural gas
  • aelb771
    aelb771 Member Posts: 7
    So I’m still waiting for the HVAC tech to come to my house, but I just wanted to give an update:

    I used my multimeter to check the voltage at the flame sense rod, and it’s only getting about 55 V. I checked the voltage on my two other furnaces, and the flame sense rod is getting 100 V. So I was thinking that it is probably a problem with the control board not supplying enough voltage. One thing I forgot to mention before, is that I had the control board replaced about a year and a half ago. I still had the box laying around the basement, so I opened the box, and saw this part that said “important install accessory “.  It’s a resistor kit, that was supposed to be attached to the flame sensor rod, but was not. The instruction sheet says that it is designed to “mitigate voltage spikes that could shorten the life of the flame sensor circuit.” I’m going to venture a guess that this may have been what caused my problem, and that I’ll probably need a new board? Just for fun, I tried installing the resistor kit, and the voltage to the flame sensor rod went down to 25 V after I installed it. Curious as to what you guys think. Thanks again.

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