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laff20

GoodMan Furnace GMS80904BNA Flame Problem

laff20
11 years ago

Furnace flame ignites till blower starts and goes off in 10 seconds 15 seconds and will ignite again and will repeat all night long or until thermostat reaches temp.. System does not lock out.
No troubleshooting codes.

Started with a bad Pressure switch (no flame at that time) did receive codes for this replaced and got flame.

What I have done so far:

Replaced mother board twice.
Cleaned flame sensor.
Cleaned evaporator coils.
Verified Thermostat
Had 2 technicians who apparently have no clue.

Any help would be appreciated.

Comments (13)

  • mike_home
    11 years ago

    Perhaps the flame sensor needs to be replaced. It is an inexpensive part and should be easy to replace.

  • laff20
    Original Author
    11 years ago

    Thanks. The flame sensor was replaced. We checked all voltages coming off the board and found 14.6 (s/b 24 volts) volts coming from the 2nd (new) board relay to the gas valve. Apparently 2 boards rec'd were bad. Trying strike 3 on Mon. Will post results

  • mike_home
    11 years ago

    If the third board also has a voltage problem, then I suspect the problem may be the transformer. Measure the voltage of the transformer output with the board disconnected. If it is not 24 volts, then you have a supply problem. If the voltage drops after attaching the board, then it may be a bad connector or the transformer can't supply the required current at 24 volts.

  • harlemhvacguy
    11 years ago

    Do you have a ground wire hooked up on the line voltage supply? These furnaces will not run well without a good ground. It requires a ground to sense flame and to maintain proper voltage from transformer.

  • harlemhvacguy
    11 years ago

    Do you have a ground wire hooked up on the line voltage supply? These furnaces will not run well without a good ground. It requires a ground to sense flame and to maintain proper voltage from transformer.

  • laff20
    Original Author
    11 years ago

    OK here is now the latest.Another tech came out today and troubleshot the unit again.

    Apparently the Pressure switch is good, but, during the stage of fire it receives 24 volts and it opens and the voltage drops out to 0 volts for a split second and cuts the flame during the start up.. Then back to 24vRepeats and repeats.

    Took a known bad pressure switch and connected. This did show the correct troubleshooting code on the board.

    My head hurts.

    Any help again would be appreciated.

  • mike_home
    11 years ago

    Is this the third control board? Is the new board an exact replacement for the manufacturer's equipment or a generic version?

    Are you monitoring the output of the transformer while the furnace is starting up? Is the voltage dropping below 24 volts?

  • laff20
    Original Author
    11 years ago

    OK check this out.

    5th technician in and fixed finally. There was a voltage drop at the pressure switch to 0 volts for a split second, if you blinked you would miss it on the meter. Apparently I was blinking and so were the other 4 guys. The drop and raise back to 24v was so fast that it did not get picked up at the control module. There's one for the books.
    Got another new pressure switch and now it works like new.I do know that every person that looked at it said the board had to be replaced including the Goodman rep.

    If you guys have any questions about this feel free to ask.

    I want to thank all that offered help and have a warm Merry Christmas. I can now.

  • mike_home
    11 years ago

    Are you saying the new pressure switch was giving a momentary false reading which confused the control board?

  • laff20
    Original Author
    11 years ago

    yes for a split second

  • rickb1958
    9 years ago

    ok this pressure switch problem is this a commen problem, i put a new one on and furnace worked fine over the weekend and my wife turned ac on last night and now the furnace wont light. it tries but fails and shows a gas fault. any thoughts

  • garyjameson
    7 years ago

    When
    we turn the temp up several degrees above the room temp, it won't come on. We hear it click and the "heat"
    indicator turns on, but the heater won't come on. Or it will run for a few minutes and then shut off, even though the room temp hasn't increased to the desired temp on the thermostat. Then after about 1 hour, it will come
    on and run correctly. This only happens about 1 time each
    week. The rest of the time it works
    correctly. There is no pattern (time of day, room temp, etc.) as to when it messes up. We have had 2 different
    heater repair men look at it numerous times, and they can't fix it. They have replaced the thermostat, the
    circuit board, the limit switches, the flame sensor, and even turned down the gas at
    the jets so the air temp is 120 degrees.
    When it doesn't work (about 1 time each week) we have checked the
    blinking red light inside the round window for a code. Each time, it blinks 1 time and pauses for 3
    seconds, then blinks again, etc. This
    code just means the system is "locked out." Any ideas what could be wrong?

  • PRO
    Austin Air Companie
    7 years ago

    Sorry to have to tell you this but intermittent problems will be tough for anyone to diagnose in person. Especially if the furnace works properly while the technician / contractor are there. Without being able to see why the furnace is shutting down or gather this information from a code on the board, you're left to guessing of which has proven to you already is futile.

    You have a few options:

    1. buy a new furnace.

    2. keep guessing at more parts and you may spend more than a new furnace.

    3. wait until it stops working completely and then diagnose the problem.

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