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After a few power outages and some very cold weather, the Goodman (GMSS960803BNAA) propane furnace at our cabin is not heating.

The thermostat is new/replaced (Nest) and I've checked voltages for the thermostat wires.

When turned on, the furnace attempts to light (see video) but for whatever reason does not end up lighting.

After three attempts, the solid red status light turns to a single blink (system lockout). No other blink statuses during ignition.

Other propane appliances in the house (stove, water heater) seem to be working fine.

I am not familiar with furnaces so any specific suggestions appreciated. I'd call an expert in to help but the cabin is not easily accessible in the winter.

https://photos.app.goo.gl/WZ8Qan3Hhertzj3X7

  • Did the furnace only stop working after the t-stat was replaced? Or has it run fine since the new stat was installed? – Paul Logan Feb 25 at 18:29
  • It was doing the same thing before. I don't know anything about furnaces so I just replaced the thermostat as a first step since I disliked the old one anyway. – jlivni Feb 25 at 18:39
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The two leads going into the gas valve should read 24 volts for about half a second just before it shuts off again if that's the case then your gas valve is no good. If you don't get 24 volts for half a second or so just before the igniter shuts off then the problem is Upstream. Possibly a pressure sensing device attached to the gas pipe doesn't allow the gas valve to open if the propane pressure is too low I don't think Goodman and uses that set up for propane conversions) you may have an issue with your circuit board. Often grounding will be the first thing people jump to, but in most cases a grounding issue causes trouble with sensing the flame. What would happen is the flame would light and then go out that's not the case here.

  • Thanks! I'll try when I stop by this weekend (assuming power is available) – jlivni Feb 27 at 4:11
  • Thanks - I tested and there was no change in voltage at any time during the attempted startup (3 attempts before it cycled into system lockout). I am guessing replacing the circuit board is the next approach? – jlivni Mar 5 at 13:05
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    Yeah it looks like the board. When you go to replace it, power down at the switch. Get as much slack on the wiring as possible and remove all the plugs that have only 1 possible connection spot. For the rest hold the replacement board next to the defective one and swap 1 wire at a time. Be very careful as a misplaced wire could lead to all kinds of trouble. – Joe Fala Mar 5 at 13:36
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Well your hot surface Igniter is glowing so therefore all for the safety's have checked out. If the other gas appliances in the house are working you have good gas pressure to the house. The manual control switch on the main valve appears to be in the on position. Make sure the isolation gas valve just before the furnace is in the on position. The only things that are left is the main automatic gas control valve and or the main control board. If you have the techno ability you need to test the ohm rating of the control valve coil. Then check to see if the main board to sending 24-volts to the valve during the time the igniter is lit. This will tell you what is wrong. Either the main control valve or the control board. Good Luck.

  • Thanks! I have a multimeter -- is the control valve coil you are referring to the same as the gas valve? I was planning to check that for 24v (per other comment) which I think I can do this weekend when I next visit, but I'm not sure about this coil thing. – jlivni Feb 27 at 4:14
  • Yes control valve is main automatic gas valve. When you check ohms. One or both of the wires need to be disconnected. – Paul Logan Mar 1 at 4:03
  • Thanks. I tested and there was no change in voltage at any time during the attempted startup (3 attempts before it cycled into system lockout). I am guessing replacing the circuit board is the next approach? – jlivni Mar 5 at 13:05

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