I have a Goodman Heater Model # GMP-100-3 Serial # 9407061708. The blower turns on and the ignition lights but the furness will not fire. If anyone knows where I can get a service manuel on this heater, or if anyone has an answer it would be greatly appreciated.
Thanks
Bill Sadowski
[email protected]

Check for 24 volts at the gas valve while the unit is running. If you have voltage at the valve but the valve is not opening then the valve is more than likely defective. You might also check the flame sensor. Normally when it does not work the furnace will shut down and try to restart.