GR9T96

This board

Self-diagnostic IFC · single 7-segment (read Seg3→Seg2→Seg1 left to right)

• Codes sit on the IFC in the blower compartment. Do not kill power — that clears the active code.
• Read left to right. Idle / no fault is a quiet or dashed display; faults prefix E, EE, L, U, F, S, r.
• E1/E2 are the LOW-FIRE pressure switch. E8/E9 are the HIGH-FIRE pressure switch. Do not treat them as the old 2-flash / 3-flash single-switch chart.
• A2L pair codes (FE3, LE4, SE5, rE6) only apply when this furnace is tied to an R-32 / A2L outdoor. Ignore them on R-410A pairs.

Sequence

1. W1. IFC proves limits/rollout closed, starts inducer on low speed.
2. Prove low PS. Low-fire pressure switch must close. If it is already closed with inducer off → E1. If it never closes → E2.
3. HSI warm. Silicon nitride igniter ~17–27 s (OEM). Open igniter → En / E7.
4. Low-fire valve. First-stage solenoid opens. Flame must prove at the rod. Failures stack toward E0 lockout.
5. Blower delay. Heat-on delay, then ECM on the selected heat tap (not a communicating CFM request).
6. W2 / high fire. Inducer goes high. High-fire PS must close (E9 if open, E8 if it was already closed). Second-stage solenoid opens.
7. Satisfied. Valve off, inducer post-purge, blower heat-off delay. Unexpected flame after valve-off → E4.

Faults on this IFC

• E0

  Retry / recycle lockout

  lockout

  Too many failed ignition attempts or flame losses on this call.

  • Watch one full try: inducer, HSI glow, valve click, flame, µA.
  • Gas supply and manifold (low then high).
  • Ground and flame-rod cleanliness.
  • Do not keep resetting — find which step dies.
• E1

  Low-fire PS stuck closed

  lockout

  Low-stage pressure switch is made with the inducer off.

  • Unplug the LPS. If code changes, switch is welded or hose is holding residual draft.
  • Hose routed downhill to the collector? Water in the hose fakes a closed switch.
  • IFC input shorted — only after the switch ohms open.
• E2

  Low-fire PS open

  lockout

  Inducer is on low and the low-fire switch will not close.

  • Inducer spinning? 120 VAC at inducer on a W1 call.
  • Collector box, inducer outlet, and condensate trap — this 96% unit will not make pressure with a full trap.
  • PVC intake/exhaust (bird screen, ice, long run, wind).
  • LPS hose cracked or on the wrong port (low vs high tap).
• E3

  Open high limit

  warn

  Primary limit opened. Airflow or overfire — not a charge problem.

  • Filter, blower wheel, A-coil, heat-speed tap (9-speed: wrong tap is the #1 callback).
  • Static vs blower chart for this cabinet size.
  • Manifold pressure on low and high vs rating plate.
  • Limit ohms after it cools — a limit that never recloses is failed.
• E4

  Flame when valve should be off

  hazard

  Rod sees flame with both solenoids de-energized.

  • Shut the gas cock. If flame stays, leaking valve — replace, do not jump.
  • Rod shorted to ground or IFC flame circuit.
• E5

  Open fuse

  warn

  3 A (typical) automotive fuse on the IFC is open.

  • 24 V short on W, Y, G, humidifier, or EAC.
  • Unplug tstat harness and replace fuse. If it blows again the short is on the board or gas valve harness.
• E6

  Low flame signal

  warn

  Flame is present but µA is below the IFC threshold.

  • Clean rod with a non-scratch pad — not sandpaper.
  • Chassis ground to burner box and IFC.
  • Manifold pressure / orifice / LP conversion.
• E7

  Igniter relay fault

  lockout

  IFC did not see the igniter circuit behave as commanded.

  • Igniter ohms cold (OEM — typically 30–115 Ω class, confirm sticker).
  • 120 VAC to igniter during warm-up.
  • Cracked nitride element.
• E8

  High-fire PS stuck closed

  lockout

  High-stage pressure switch is made with the inducer not on high.

  • This is the second switch — do not confuse with E1.
  • Welded HPS or water-filled hose.
  • IFC calling high when it should be low — W2 shorted to W1.
• E9

  High-fire PS open

  lockout

  Inducer on high, high-fire switch never closes. Classic ‘runs on low, will not go high.’

  • Inducer actually changes speed on W2? Listen / amp it.
  • HPS hose on the high-fire tap, not teed to the low switch.
  • Vent capacity / wind / shared chase. High fire needs more draft than E2 ever saw.
  • Condensate backing into the collector only under high fire.
• EA

  Line polarity / ground

  lockout

  L1/N reversed or chassis ground missing. HSI and flame sense both suffer.

  • Hot and neutral at the IFC, not just the disconnect.
  • Burner box to IFC ground screw.
  • Twinned jobs — follow the twinning kit, then look at EEJ.
• Eb / Ec

  Gas valve circuit

  lockout

  Internal (Eb) or external (Ec) gas-valve electrical fault.

  • Valve coil ohms, 24 VAC at the harness during trial.
  • Do not apply 24 V to a leaking valve as a ‘test’ and walk away.
• Ed

  Open rollout

  hazard

  Manual-reset rollout opened. Treat as flame outside the exchanger until proven otherwise. Door chart may render this as a distinctive 7-seg character — confirm on the unit sticker.

  • Primary exchanger cracks, burner alignment, crossover.
  • Blocked secondary / condensate / flue.
  • Reset only after the cause is fixed. Recurring rollout is a CO / fire call.
• En

  Igniter open

  lockout

  Igniter circuit measures open.

  • Ohms at the igniter plug, then at the IFC.
  • Harness rub-through on the collector.
• EEH

  Grounding error

  lockout

  IFC failed its ground check (sister to EA).

  • Green ground to cabinet and IFC.
  • Painted screw, missing star washer.
• EEJ

  Twin error

  lockout

  Twinning miswire or twin terminal active on a standalone unit.

  • If not twinned, nothing should be on the TWIN terminal.
  • Twinned pair must be same family / same IFC revision.
• LE1 / UE2

  Circulator current

  lockout

  ECM current too low (LE1) or unexpected (UE2).

  • Harness seated at motor and IFC. 9-speed ECM is tap-driven — a half-seated plug throws these.
  • Locked rotor, wet winding, or wrong motor for the cabinet.
  • Do not put a PSC motor or a ComfortBridge serial motor on this IFC.
• FE3 / LE4 / SE5 / rE6

  A2L mitigation

  hazard

  Leak / comm / relay alarm from the A2L board when paired with R-32 or R-454B outdoor.

  • Only valid on A2L pairs. On 410A, this is a miswired mitigation harness.
  • Leak sensor location, ventilation blower, and OEM mitigation sequence before you condemn the IFC.

Workflows

Test points

Flame rod

Typically ≥ 1.0 µA DC on this IFC family — confirm door chart. Rising while running is the goal.

Manifold low / high

Natural ~1.6–1.9 / 3.2–3.5 in. w.c. class — rating plate wins. Clock input if in doubt.

LPS / HPS

Both NO. Closed only when that inducer speed is making the collector setpoint. Never teed.

HSI

Nitride, 120 VAC during warm-up. Cold ohms per sticker — do not use a 80% Norton chart.

ECM heat tap

Match the installer’s tap to the rise range on the rating plate (typically 35–65°F).

Gotchas

• Techs treat GR9T96 like GMVC96 and start looking for ComfortBridge menus. There are none.
• E2 vs E9: fixing the trap clears low fire and the callback is ‘still no high fire’ because the HPS hose was never on the high tap.
• 9-speed ECM on the wrong heat tap is the silent E3 generator. It is not a bad limit.
• GD9T96 is the downflow twin — drain and secondary orientation change, codes do not.
• Amana AR9T96 is the same IFC and the same chart. Do not pull a GMVC96 communicating board or a GMEC96 CT motor into this cabinet.
• Warehouse ‘Goodman 96% IFC’ often ships the communicating board. It will not run this 9-speed motor.

Related plates

• amana-ar9t96 — Amana badge twin — same PCBBF132 IFC, same E0–E9 dual-PS chart.
• goodman-gmvc96 — ComfortBridge VS cousin. Triple 7-seg + 14-pin serial motor. Do not swap IFCs.
• goodman-gmec96 — Two-stage 96% with a CT / X-13 motor. Same E1/E2/E8/E9 physics, different blower plug.
• goodman-gmss96 — Single-stage flash-code 96%. One PS. The ‘Goodman 3-flash’ board.