Goodman GM9S / GMVC96 condensing gas furnaces: quick sheet

Covers: Goodman 96% condensing furnaces: GM9S96 / GM9S80 (single-stage, LED flash codes) and GMVC96 (two-stage, variable-speed). Amana and Daikin badge similar platforms. Some newer boards use a 7-segment display instead of a single LED.

Cross-checkedBrands: Goodman, Amana, Daikin7 components

The most common builder-grade condensing furnace in the US. Fault codes are read through the sight glass in the blower door: count flashes on the board LED. Do not cut power before reading the code, since that clears it.

Safety first

Gas valve, burners, heat exchanger and venting are blocked.
Read the LED code before cutting power; then lock out 120 V before working.
Rollout trips are a CO risk: do not bypass or repeatedly reset.

How it works

Standard condensing sequence: inducer → pressure switch closes → hot-surface ignition → gas valve → flame sensed → blower on.

LED steady on = normal; LED off = no power; rapid flash = reversed polarity.

Condensate from the secondary heat exchanger drains through a trap; a blocked trap or wet pressure tubing is a classic cause of 3-flash lockouts.

Components & tests

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Official manufacturer documentation

Always confirm values against the tech sheet for the exact model.

OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work. © 2026 OnCall Tech. Original content; not a reproduction of any manufacturer document.Generic part photos (not of this brand): Ductless mini-split indoor head mounted high on a wall by NEOSiAM, Pexels License

Diagnostic guides for this appliance

Component test · Furnace

How to test a gas furnace draft pressure switch (electrical and draft checks only)

The pressure switch proves the inducer is pulling enough draft before ignition is allowed. Test it with a meter (24 V across it) and a manometer against the set point printed on the switch. Gas valve, gas pressure and burner work are not covered: refer those to a licensed gas technician.

5 steps ~30 minadvanced

Guide · Furnace

Furnace runs no heat (blower only or nothing)

Start with the board LED code, then work the call path: thermostat, 24 V, safeties, inducer, ignition, flame proving. Most no-heat calls end at a filter, a flame sensor, a pressure switch issue or gas being off.

5 steps ~45 minmoderate

Guide · Furnace

Furnace short cycling (starts and stops quickly)

Short cycling is usually a safety opening mid-cycle (limit from low airflow, flame sensor dropping out, pressure switch opening) or a thermostat issue. Read the code and time the cycle.

4 steps ~45 minmoderate

Other furnaces manuals

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80% gas forced-air furnace: field service manual

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Manual · Furnace

90%+ condensing gas furnace: field service manual

High-efficiency condensing furnaces (about 90-98% AFUE) with a secondary heat exchanger, PVC venting and a condensate trap; single-stage, two-stage and modulating

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Electric furnace / air handler with heat strips: field service manual

Electric furnaces and air handlers with resistance heat strips, sequencers or relays, and limits/thermal links

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