Hi Marta, I would start by replacing the flame sensor. What wire did you re-splice?
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- posted
9 years ago
My gas furnace won't shut off (heat and blower keep running)
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- posted
9 years ago
Here is my situation: Guardian 80% GG8S120C16MP11A; 2 years old A few months ago, I installed a new thermostat (Honeywell RTH2300B1012/A), and replaced the two wire with a three wire. Everything ran fine, no issues. Yesterday, we had the gas line added to the existing water heater gas line. The furnace has its own gas line running from the main line, and nothing was touched running to the furnace. We shut down the main gas and turned the thermostat to "Off." My spouse may have turned it back to "Heat" and turned the temperature way down when the furnace didn't turn off right away, but in any event the furnace did not turn on at any point during the gas line work. After the work was complete, we powered up the water heater and then the furnace. Both ran fine, however, the furnace kept running, and running, and running (blower and heat). When it was 75 degrees, I realized we had a problem. Here the steps I proceeded to take:
- Turned the thermostat down, waaaay down, and the blower and heat (gas) kept running.
- Turned the thermostat to "Off" and it (blower and gas) kept running.
- Powered down the furnace and disconnected the thermostat wire at the thermostat. Powered the furnace back on and the blower and heat kicked right back on.
- Checked the LED fault code on the furnace control panel: Long red flash, which is identified as flame was sensed when there was not a call for heat. This makes sense to me, as that is exactly what is happening.
- Powered down the furnace and disconnected the thermostat wires in the control panel in the furnace. FINALLY I heard the furnace power on when we turned it back on, but this time the blower and heat DID NOT turn on. So it seems to me that the issue is with the wiring, not the furnace and not the thermostat, as it still runs the heat and blower when the wiring is fully disconnected from the thermostat. Can someone help me identify what is going on? Is there a short in the wiring? There is a portion that I had to cut and re-splice--could this be the issue? How would I troubleshoot this? Thank you!