Goodman GMEC960803BN Error Code Green 1 Flash: Normal Operation - Low Stage Cooling (Ylo + G)
What Does Code Green 1 Flash Mean?
A single green flash on the Goodman GMEC960803BN's Integrated Control Module indicates normal operation with a low-stage cooling call. The thermostat is energizing the Ylo and G terminals, so the board runs the indoor blower at its cooling speed while the outdoor unit provides low-stage cooling.
This furnace board supports staged cooling: green 1 flash is the low-stage cool indication and green 2 flashes is the high-stage or single-stage cool indication. Running on low stage is quieter and more efficient, and the system steps up to high stage only when more cooling capacity is needed.
Because green indicates a normal state, a single green flash during air conditioning is expected and requires no action. It confirms the furnace blower and the board are correctly responding to your cooling equipment.
What You'll Notice
- Cool air from the registers while the air conditioner runs at its lower, quieter stage
- A single green flash on the control board during a cooling call
How This Is Diagnosed
No diagnosis is needed — this is a normal low-stage cooling indication. If cooling is weak or the system never steps up to high stage when it is very warm, the thermostat staging setup and the outdoor unit are checked, but the green 1-flash indication itself simply confirms the furnace blower is responding correctly to the low-stage cool call.
- The blower shows this cooling indication but little or no cool air is produced — the outdoor air-conditioning unit, not the furnace board, is the likely area to investigate
Frequently Asked Questions
What does one green flash mean on my Goodman furnace?
It indicates normal low-stage cooling operation. The thermostat is calling for low-stage cooling (Ylo + G) and the furnace blower is running to move the cooled air.
Why is the furnace board flashing during summer when I only use the AC?
The furnace's control board also runs the indoor blower for cooling. A single green flash during air conditioning just confirms the blower is responding to a low-stage cool call — this is normal.
✓ Verified against manufacturer service manual — March 2026