I have a Goodman GMP100-3 furnace that will not fire up. It's been giving me
problems for a few weeks now but finally quit altogether. Early symptoms were as
follows: Draft induction motor would turn on - after a few seconds, the HSI
would glow - the gas valve would open and the gas would fully ignite across all
four orifices - after 20 seconds or so, the main blower would turn on and
immediately the gas valve would close and flame would go out - after another
20-30 seconds the HSI would glow, valve would open, gas ignite and furnace would
run it's cycle without occurrence until the next time the thermostat called for
Later symptoms would be similar to the earlier ones (mentioned above) but would
include the gas valve closing even after the main blower was running and flame
had been burning for several seconds. Now the gas won't ignite at all, even
though I can hear the gas valve click.
After three tries, I got a single flash from the diagnostic LED (ignition
failure). So, I tried cleaning the flame sensor...didn't help - I tried
replacing the flame sensor...didn't help - I tried bypassing all the temp
sensors and connecting the gas valve directly to the control board's purple wire
(removed from 1st temp sensor [in series])...didn't help.
I'm getting 27 AC volts to the gas valve and am hearing the right (output side
of valve) solenoid click when the control board calls for gas. However, I'm not
hearing or feeling the left (inlet side of valve) solenoid click. Almost seams
like a week solenoid. Are both solenoids supposed to open together? Why are
there two solenoids? Is this for safety....to make sure the valve closes....in
case one valve sticks open? I's there a way to test this valve further?
Any help would be appreciated.