FieldBench

Goodman

GMSS96

Furnace · Single-stage · 96% AFUE · LED flash

Single-stage 96% condensing furnace with one pressure switch and a red LED flash-code IFC. This is the board most ‘Goodman 3-flash’ videos are actually about — not GR9T96, not GMEC96, not GMVC96.

Not GR9T96 (two-stage, dual PS, 7-seg E1–E9). Not GMEC96 (two-stage CT motor, E0–E9). Not GMVC96 (ComfortBridge VS, triple 7-seg). Do not alias those cabinets onto this chart.

Walk this in Diagnose

This plate

Staging
Single-stage gas valve · single-speed inducer · one pressure switch
Blower
Multi-speed ECM or PSC depending on exact SKU
Display
Red LED flash chart — not a 7-segment E-code
Tstat
Conventional 24V · W Y G R C
Sister SKU
GM9S96 / GCSS96 · Amana AM9S96 same flash family

This board

Single-stage LED IFC

  • LED off = no 120/24. LED steady on = idle with 24 V present. Rapid flash = reversed polarity, not a high count.
  • Count flashes between the long pause: 1 lockout, 2 PS closed inducer off, 3 PS open inducer on, 4 limit, 5 flame valve off, 6 rollout, 7 low flame, 8 igniter, 9 polarity/ground.
  • One pressure switch only. Do not apply E8/E9 high-fire codes — there is no high-fire switch.

Sequence

  1. W. Inducer on → single PS must close → HSI → valve → flame → blower delay.
  2. No W2 path. There is no high-fire prove. A leftover W2 wire is unused or tied for an AC stage, not furnace high fire.

Faults on this IFC

  • LED off

    No power

    warn

    No 120 VAC or no 24 VAC on the IFC. Not a flash code.

    • Door switch, incoming L1/N, transformer, 3 A fuse.
    • If 24 V is present and the LED is dead, IFC.
  • Steady on

    Idle

    info

    24 V present, no call, no fault. Status.

    • If the house is cold, the call is not reaching W. Check R to W at the IFC, not just at the stat.
  • Rapid flash

    Polarity reversed

    lockout

    L1/N swapped. Not ‘code 10’ and not a high flash count.

    • Hot and neutral at the IFC, not just the disconnect.
    • Burner-box ground. Rapid flash is EA-class, not a PS.
  • 1 flash

    Retry lockout

    lockout

    Ignition retries exceeded on this call.

    • Watch a try: inducer, HSI, valve, flame.
    • Gas, rod, ground. Do not keep resetting.
  • 2 flash

    PS closed, inducer off

    lockout

    The single switch is made with the inducer not running.

    • Unplug the PS. Hose water holding residual draft.
    • Welded switch or IFC input shorted.
  • 3 flash

    PS open, inducer on

    lockout

    Draft not proven. The call you will see all winter on 96% Goodman singles.

    • Trap and collector first — these 96%s drown overnight.
    • Inducer 120 VAC and spinning. Hose on the only collector tap.
    • PVC intake/exhaust, bird screen, ice, wind.
  • 4 flash

    Open limit

    warn

    Airflow or overfire.

    • Filter, heat-speed tap, rise, coil.
    • A 96% coil on a furnace left on a low heat tap will limit all season.
  • 5 flash

    Flame with valve off

    hazard

    Leaking valve or false flame sense.

    • Shut the gas cock. If flame stays, replace the valve.
    • Rod shorted to ground.
  • 6 flash

    Rollout open

    hazard

    Manual-reset rollout. Flame containment until proven otherwise.

    • Exchanger, burners, crossover, flue, secondary / condensate.
    • Reset only after the cause is fixed.
  • 7 flash

    Low flame

    warn

    Weak µA.

    • Clean rod, chassis ground, manifold, LP conversion.
  • 8 flash

    Igniter fault

    lockout

    Open / cracked HSI or no 120 VAC during trial.

    • Ohms at the igniter, then at the IFC.
    • 120 VAC during warm-up. Nitride, not an 80% Norton chart.
  • 9 flash

    Polarity / ground

    lockout

    L1/N or chassis ground. Sister to rapid flash on some revisions.

    • Hot/neutral at the IFC.
    • Burner box to IFC ground screw.

Workflows

3-flash no heat

Inducer runs, no ignition, LED 3-flash. Overnight no-heat is the classic.

  1. Count flashes. Do not open a GR9T96 E-code card on this board.
  2. Prove inducer 120 VAC and spinning.
  3. Open the trap and the collector — 96% Goodman singles drown overnight. That is the call.
  4. Hose dry and on the only tap. Ohms the PS with inducer on (should close) and off (should open).
  5. If PS closes and IFC still 3-flashes, IFC input is the fault.
  6. PVC termination: ice, bird screen, wind. One switch — there is no ‘high-fire hose’ to move.

Test points

Single PS
One NO switch. Closed only with inducer up. If you see a second hose hanging, someone mixed this cabinet with a two-stage collector.
Manifold
Single-stage plate value only — no low/high pair.
LED
Off / steady / rapid / 1–9 counted between the long pause.

Gotchas

  • Do not install a second pressure switch ‘because two-stage boards have two.’
  • A leftover W2 from a previous two-stage furnace does nothing useful here and confuses the next tech.
  • GMEC96 and GMVC96 are not this board. Flash-count videos that cut to a 7-seg are a different furnace.

Related plates

  • goodman-gmec96 — Two-stage CT 96%. Dual PS, E0–E9. Not a flash board.
  • goodman-gr9t96 — Two-stage 9-speed. Dual PS, single 7-seg E0–E9. Not 3-flash.
  • amana-am9s96 — Amana-badge single-stage flash twin.