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ekg125 · Sep 28, 2008, 06:43 AM

I have a Goodman GMP075-3 furnace. The draft inducer comes on, the control board clicks, the ignitor bar glows, the control board clicks again and the glow bar stops glowing. It seems like the gas valve isn't opening to allow gas to ignite, at all. I've replaced a rollout switch, the flame sensor and the control board. What's next? The pressure switch seems to be fine as I can blow and suck in it to make it open and close. I can do the same with the inducer by blowing into the hose and air goes through it without a problem. Could the limit switch need replacing? How about the pressure switch? I haven't put a volt meter on the pressure switch to see if it's passing 24 volts yet. Is it possible that the gas valve itself has gone kaput? I know that Goodman furnaces aren't the best in the world, but I can't afford to replace it just yet. I'd like to be able to make it through this winter first, then I can purchase a new furnace in March.

ekg125 · Sep 28, 2008, 10:18 AM

I just checked and the pressure switch and limiter are both reading 28 volts. What now?

hvac1000 · Sep 28, 2008, 03:00 PM

If you have a flame sensor clean it.

mygirlsdad77 · Sep 28, 2008, 05:36 PM

Do you have one or two pressure switches? If you are putting your tester leads to the two terminals on the pressure switch, you should not be reading 28 when the pressure switch is closed.
Turn the power of to the furnace, then turn it back on and wait for about three seconds, then phisically suck on the hose to the pressure switch, make sure you suck hard enough to keep the switch closed. See if the furnace lights.
Please let me know if this works, if not , we will go to step two.
I have worked on goodmans, they are actually a very good funace(at least the newer ones) very easy to trouble shoot and fix.

ekg125 · Sep 29, 2008, 05:03 AM

HVAC1000, I tried cleaning the flame sensor once, with some fine steel wool, but it didn't work, so as I stated, I have replaced it altogether, along with 1 rollout switch and a new control board.

Mygirlsdad77, I have only 1 pressure switch, and will be trying your advice as soon as I drop the kids off at school.

I should also add that, after the control board clicks the first time, and the ignitor bar begins to glow, there is a second click. After the second click, I get a 27 volt reading on the gas valve, but the ignitor bar turns off, then it fails. After 3 tries, the board displays 1 flashing light (ignition failure).

hvac1000 · Sep 29, 2008, 05:13 AM

With voltage at the gas valve it should open.

ekg125 · Sep 29, 2008, 07:33 AM

mygirlsdad77, I pulled the hose from the inducer and sucked through it, heard the pressure switch close, but the ignitor bar never glowed. I also tried putting my finger over the hole on the inducer and sucked through the hose, but still never got the bar to glow. The only time it would glow is when I put the hose back on the inducer. It never achieved ignition.

HVAC1000, It never showed any voltage to the gas valve until the control board clicked the first time, then I heard, and could feel the valve click, too, as I had my finger resting on it as I was checking voltage. Then is when it showed 27 volts. Something seems to be telling it to NOT send any gas to the ignitor.

hvac1000 · Sep 29, 2008, 09:22 AM

With voltage at the gas valve it should open and lite if the gas valve on the valve itself and all other gas valves are turned on.!

ekg125 · Sep 29, 2008, 01:01 PM

Thanks to both of you guys. My next door neighbor is an electrician and came to help me out. It turns out that the gas valve had gone bad somewhere down the line, and wasn't opening when it was told to. We went to a local HVAC supply house and bought a replacement gas valve for $50, installed it an viola! I now have HEAT! Glorious HEAT!

Thanks again for all your help!

hvac1000 · Sep 29, 2008, 01:06 PM

Good deal and remember if you have power to the valve it should work.

mygirlsdad77 · Sep 29, 2008, 03:47 PM

Glad you got it fixed. Take care and stay warm.