HVACopediaGoodman · Furnace troubleshooting
Furnace in lockout - how to reset it
What is going on
The furnace has stopped after its ignition retries and the control is flashing 1 on the LED. That is a lockout, and resetting it only clears the symptom, not the cause. Know the reset methods, but find out why it failed to light. Never bypass a safety to force it to run.
Likely causes
- Ignition failed three times (see 1 flash)
Check in this order
- Turn the thermostat call off for more than 5 seconds and less than 20 seconds, then call for heat again.
- Or turn off the furnace disconnect for at least 5 seconds.
- The control also resets by itself an hour after lockout.
- If it keeps locking out, fix the cause with the 1 flash steps.
- LED flash codes clear when power to the control is cut, including by the door switch, so note the code before opening the door.
- If it relocks repeatedly, stop resetting and have a licensed technician diagnose the gas and ignition system.
Applies to: GMES9, GCES9, AMES9, ACES9, VMES9, VCES9 (single stage, 92% and 96%)
More furnace guides
- Airflow lower than demanded, furnace runs on low stage when high stage is expected
- Alternate combustion air opening (upflow or horizontal)
- Alternate vent/flue location (upflow or horizontal left)
- Annual inspection checklist
- Auxiliary limit control (location and purpose)
- Auxiliary limit switch open (blower compartment)
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Source: Goodman Service and Troubleshooting GMES9*/GCES9*/AMES9*/ACES9*/VMES9*/VCES9* (RS6612016r3) , Heating - Abnormal Operation p.26. Written in our own words; check the manual for your exact model.
For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.