Goodman furnace 1 green flash: Normal operation — low stage cooling

One green flash means the furnace is running its blower for low stage cooling. The furnace itself is not heating — it is supplying air for the air conditioner or heat pump.

Applies to: Goodman GMEC96 and Amana AMEC96 two-stage gas furnaces with a three-colour diagnostic LED, running the indoor blower for a cooling call.

What it means

The furnace cabinet contains the indoor blower that the cooling system also depends on, so the furnace control runs during cooling even though no gas is burning. Green on this board means a cooling call: one flash for low stage cooling, two for high stage or a single-stage compressor. Someone who opens the panel in summer, sees a light flashing, and starts counting will find a code that does not appear on any fault list, because it is not a fault. The furnace is acting as the air handler. Worth knowing alongside it: on this board green never indicates a problem. Faults are red, and status is amber or green.

Most common causes

The thermostat is calling for low stage cooling, with the compressor running on its lower capacity.
A two-stage outdoor unit operating on first stage, which is normal in mild weather.
The blower running on the cooling speed, which is the furnace's role during a cooling call.

How to diagnose it

Confirm the flashes are green rather than red or amber.
Note whether the house is cooling. If it is, nothing here needs attention.
If the blower runs but no cool air arrives, the problem is in the cooling equipment or refrigerant circuit, not in this code.
Two green flashes means high stage cooling, and is equally normal.

How to fix it

Nothing. This is a normal operating indication.
If cooling performance is the actual complaint, the furnace control is reporting that its part is working — look at the outdoor unit.

Notes

Because the furnace runs the blower for cooling, its diagnostic LED is showing something all summer. That is often the first time a homeowner notices the light at all, which is why a normal cooling indication gets mistaken for a fault stored over the winter.

All codes for this manufacturer

Goodman and Amana furnace fault codes — every code, with what differs between models.

Sources

Goodman Manufacturing — Diagnostic Code Identification System (model-specific fault code lookup)

This site is a reference, not a substitute for a licensed HVAC technician. Gas appliances can leak carbon monoxide and cause fire. Anything involving gas lines, the heat exchanger, or the flame sensing circuit should be handled by a licensed professional. Pages are written with AI assistance from the sources listed on each page and checked against them before publishing.