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Goodman gas furnace 1 green flash: Low-stage cooling call

Gas furnace, Canada and United States

One repeating green flash means normal operation with the thermostat calling for low-stage cooling (Ylo and G).

You can often clear this yourself. Work through the causes below in order, most likely first.

What causes it

  1. This is normal. If cooling seems weak, check the air filter first; dirty filters are the most common cause of poor heating or cooling.

    Check and replace the furnace air filterYou can do this

    1. Turn off the electrical power to the furnace before you take the filter out.
      Never run the furnace without a filter in place.
    2. Find the filter. It sits outside the furnace cabinet, in a return air grille, a filter rack on the side of the furnace, or the duct next to it. If you cannot find or reach it, ask your installer.
    3. Replace a dirty disposable filter with one of the same size that meets UL900 or CAN/ULC-S111. Wash and dry a permanent filter the way its maker describes.
    4. Fit the filter so the air flows through it in the same direction as before, then turn the power back on.
    5. Check the filter at least once a month and clean or replace it when it is dirty. A dirty filter is the most common cause of a furnace not working properly.

How to read this code on your unit

Models that show this code

30 models in 1 range
RangeModels
GMEC96 / GCEC96 / AMEC96 / ACEC96GMEC960302BN, GMEC960303AN, GMEC960402BN, GMEC960403AN, GMEC960603AN, GMEC960603BN, GMEC960803BN, GMEC960804CN, GMEC961004CN, GMEC961005CN, GMEC961205DN, AMEC960302BN, AMEC960303AN, AMEC960402BN, AMEC960403AN, AMEC960603AN, AMEC960603BN, AMEC960803BN, AMEC960804CN, AMEC961004CN, AMEC961005CN, AMEC961205DN, GCEC960403BN, GCEC960603BN, GCEC960803BN, GCEC961005CN, ACEC960403BN, ACEC960603BN, ACEC960803BN, ACEC961005CN

Where this comes from

Checked against the manufacturer's manual on 9 October 2026.

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Other Goodman gas furnace codes

Code Meaning What you can do
IdL Idle, normal operation You can often fix it
1 amber flash Low-stage heat call You can often fix it
2 amber flashes High-stage or single-stage heat call You can often fix it
3 amber flashes Second-stage heat call without first stage Safe checks first, then a pro
4 amber flashes Cooling call without a fan signal Safe checks first, then a pro
amber light flashing rapidly Weak flame signal Call a pro
2 green flashes High-stage or single-stage cooling call You can often fix it
green light flashing rapidly Fan-only call You can often fix it
steady green light Standby, waiting for a call You can often fix it
light off No power to the control board Safe checks first, then a pro
steady red light Normal operation or control board internal fault (depends on model) Depends on your model
On Normal operation You can often fix it

See all normal operation codes on gas furnaces across brands.