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Goodman GMNT060-3B

Goodman
Goodman Member Posts: 4
in Gas Heating

I've tried four mother boards (2 with newer components and 2 with the original components, all with the same part number) on this furnace. The newer boards will get to opening the gas valve and then do one of the following. Supply flame anywhere from 1 sec to 5min then the flame puffs out. Recycles and puffs out immediately. When powering up with the orig. mother boards, all it does is cause the transformer to make a clicking sound and tries to start the inducing motor. I had a hvac company come out and after 3 technicians and 9 hours work, they could not figure out the gas valve puffing out issue. The transformer clicking is a new problem. I replaced the transformer, and it responded the same way. Please advise.

Comments

  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,388

    You have 7 safeties wired between the w terminal on the thermostat and the gas valve. I would guess the inducer pressure switch is the most likely offender. Disconnect the switch and blow out the tubing connected to the switch and make sure they are all clean. Some of these safeties may be auto reset or manual reset.

    You can also start the furnace and jumper the two switch wire to see if the furnace will continue to run.

    DO NOT UNDER ANY CIRCUMSTANCES LEAVE THE JUMPER IN PLACE>

    Goodman
  • Goodman
    Goodman Member Posts: 4

    I did what you advised to no avail. Quite literally the second power is supplied to the furnace, the transformer starts clicking. It keeps trying to power up, but it seems like the voltage is dropping out on each click. Thanks for responding to my post.

  • HVACNUT
    HVACNUT Member Posts: 6,298

    Transformers don't click. Unless they're on fire. But even then it's more of a pop.

    9 hours is a long time to come up empty handed. What's the serial number on the Goodman furnace?

    IronmanGoodman
  • Jamie Hall
    Jamie Hall Member Posts: 24,720

    Transformers don't click. Particularly not repeatedly. Relays do. Find the relay which is clicking, and then find out what powers it…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Ironman
  • Ironman
    Ironman Member Posts: 7,539

    Check and make sure that all ground wires in the furnace and all the way back to the electric panel have good connections. The ignition system uses the ground with micro voltage passing through it to prove the flame.

    Also: has the flame rod been replaced?

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    Goodman
  • 109A_5
    109A_5 Member Posts: 1,587
    edited November 28

    Hello Goodman,

    Assuming the 4 boards are all in good working condition but the symptoms change with the design generation difference. I would suspect the flame sensor and/or its wire and/or the ground wire is defective or compromised, inspect carefully and measure the resistance of the wire if you can. Since with the design change the flame proving electronics, method, sensitivity may be a bit different, so the boards behave differently.

    If you have not gone through the Sequence of Operation it may help.

    image.png
    image.png

    https://www.questargas.com/ForEmployees/qgcOperationsTraining/Furnaces/Goodman_GMNT.pdf

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    Goodman
  • Goodman
    Goodman Member Posts: 4
    edited November 28

    S/N 0310040906 I replace the flame sensor. Same results.

  • Ironman
    Ironman Member Posts: 7,539

    Also be advised that you’re past the normal life expectancy of that furnace.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • pedmec
    pedmec Member Posts: 1,060

    Remove all your low voltage thermostat wires from the IFC and then jumper R to W. What happens when you do that.

    hint: take a pic before disconnect so you know where to put everything back

  • 109A_5
    109A_5 Member Posts: 1,587
    https://forum.heatinghelp.com/discussion/comment/1823095#Comment_1823095

    What about the flame sensor wire and the ground wire ?

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Goodman
    Goodman Member Posts: 4

    I want to thank you all for replying to my post. It turns out it was the thermostat. Last summer the batteries died on it and the corroded. I cleaned it up and it worked fine with the A/C. That is why I didn't check it right away. Thanks to the two posts that suggested bypassing the thermostat. Believe it or not, I have an old Honeywell coil/mercury thermostat. Works great until I buy a digital one. Fixed in the nick of time. Supposed to be high 29 low 16 for the next 4 days.

  • 109A_5
    109A_5 Member Posts: 1,587

    Glad you figured it out. The old Honeywell may keep you more comfortable during heating session if the heat anticipator is set correctly. Mine has worked flawless for 50 years.

    WoW that may be a record, 4 boards, 3 technicians and 9 hours work to NOT find a bad thermostat.

    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
    LRCCBJ
  • HVACNUT
    HVACNUT Member Posts: 6,298

    3 techs, 9 hours. Forget doing an Ohms test. Nobody even jumped R and W at the board. Awesome.

  • pecmsg
    pecmsg Member Posts: 5,283
    https://forum.heatinghelp.com/discussion/comment/1823183#Comment_1823183
    https://forum.heatinghelp.com/discussion/comment/1823197#Comment_1823197

    Tough finding good help today.

    LRCCBJ

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