GR9S96

IFC internal fault or interrupt loss.

1. 1 Write the live code and watch one cycle

   On Goodman GR9S96 read Self-diagnostic IFC · single 7-segment (Seg3→Seg2→Seg1) before you pull power. Write EEE exactly. Watch one full sequence and note which step dies. Power cycle once. Repeat EEE = board, after 120/24 and the door switch are proven.

   Expect: W: IFC proves limits/rollout closed, starts the single-speed inducer.

2. 2 Prove the circuit this code names

   Use the Goodman GR9S96 door card and the test points on this plate. Isolate the named switch, sensor, or output with a meter — do not swap the IFC first.

   Expect: Pressure switch: One NO switch. Closed only with inducer up.

3. 3 Confirm with a number, then the next part

   If the named part measures good, the IFC input/output or a related code on this same plate is next. Do not apply a sister-SKU chart.

   Expect: Display: Three characters left to right. EE1 ≠ E11.

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

1. 1 Measure µA while it is running

   Do not clean first and guess. Series-µA the rod on Goodman GR9S96 during a call. Falling µA is oxide, ground, or a dying flame. A hard drop is often the pressure switch or limit opening, not the rod. Watch one full try: inducer, HSI, valve, flame, µA.

   Expect: Flame rod: µA per this door card — not the GMSS96 flash sticker.

2. 2 Rod, ground, then gas

   Clean the rod with a non-scratch pad — not sandpaper. Chassis ground to burner box and IFC (painted screw and missing star washer are classic). Then manifold on the stage that is dropping and confirm LP conversion leftovers. Gas, rod, ground. Do not keep resetting.

   Expect: Manifold on the rating plate. Solid burner-box ground.

3. 3 Prove it is not a switch opening

   Watch the live Goodman GR9S96 display when flame drops. A PS or limit code that appears at the drop means the rod was a victim. Inducer, hose, vent wind, or a limit on a wrong heat tap.

   Expect: µA stable and the live code stays a flame code — then rod/valve/IFC. Otherwise chase the new code.

The only pressure switch is made with the inducer off. Display is E E 1 — not E11 (rollout).

1. 1 Treat this as flame outside the exchanger

   Do not reset the Goodman GR9S96 rollout and walk away. Write the code, kill the call, and look for flame at the burners, crossover, and vestibule before you do anything else.

   Expect: No flame outside the exchanger. Burners seated. Crossover lit.

   If pass: Still inspect secondary / flue / condensate before you reset.

2. 2 Secondary, condensate, and flue

   Blocked secondary, drowned collector, or a plugged flue pushes flame out the front. Pull the inducer/collector look, confirm the trap is flowing, and check PVC/vent. Unplug the PS. If the code changes, switch is welded or the hose is holding residual draft. Hose downhill to the collector? Water fakes a closed switch.

   Expect: Dry collector, open flue, trap clear.

3. 3 Reset only after the cause is fixed

   Manual-reset rollout. Recurring rollout on Goodman GR9S96 is a CO / fire call — cracked primary, misaligned burners, or a failed secondary. Confirm CO in the space before you leave.

   Expect: One clean cycle after the cause is fixed. No second reset as a repair.

Inducer is on and the only switch will not close. The winter 96% call on this new 7-seg single.

1. 1 Prove inducer and the live code

   Do not pull power — that clears the Goodman GR9S96 active code. Write EE2. Is the inducer spinning on this call? Silent inducer is not a pressure switch. Inducer 120 VAC and spinning.

   Expect: 120 VAC at the inducer on a heat call. Wheel turning.

   If fail: 120 VAC missing → IFC / door switch / incoming power. Voltage + dead motor → inducer.

   If pass: Inducer running + this code → trap, hose, switch, vent (step 2).

2. 2 Trap, collector, and the hose

   A drowned 96% trap will not make collector pressure. Pull the trap, flush it, confirm the collector box and inducer outlet are not full. Hose cracked, off the port, or full of water fakes an open switch. Collector, trap, PVC intake/exhaust, ice, wind.

   Expect: Trap flowing, hose dry and downhill, ports not swapped on a two-switch board.

3. 3 Switch ohms, then vent load

   Ohm the pressure switch: NO, must close when that inducer speed is making the collector setpoint. If the switch is good, walk the PVC — bird screen, ice, long 2" run, wind, shared chase. Hose on the only tap. There is no high-fire hose to move.

   Expect: Pressure switch: One NO switch. Closed only with inducer up.

   If fail: Replace the open switch only after the vent and trap are proven.

   If pass: Switch closes on draft and the code stays → IFC input.

Primary limit opened. Airflow or overfire.

1. 1 Airflow before you touch the limit

   On Goodman GR9S96 a limit is airflow or overfire until proven otherwise. Do not replace the limit first. Filter, blower wheel, A-coil, and the heat-speed setting for THIS motor (tap, model plug, or communicating CFM — not a sister SKU chart). This is a 9-speed ECM. Read the heat tap before you replace a limit.

   Expect: 9-speed heat tap: Match the installer’s tap to the rise range on the rating plate (typically 35–65°F).

2. 2 Measure static and temperature rise

   Total external static vs the Goodman GR9S96 blower chart for this cabinet size. Supply minus return rise after 8–10 minutes. A new 5" media cabinet or closed supplies will trip this all winter. Filter, coil, TES vs the GR9S96 blower chart for this cabinet (A/B/C/D).

   Expect: Rise typically 35–65 °F — rating plate wins.

   If fail: Fix the restriction or the heat-speed setting. The limit is doing its job.

   If pass: Airflow in range → step 3 (overfire / limit itself).

3. 3 Overfire, then the limit circuit

   Clock the meter / manifold on the stage that is tripping vs the rating plate. Then ohm the limit after it cools — a limit that never recloses is failed. Rollout in the same circuit is a different call (see rollout on this door card). Manifold vs plate — overfire trips limits with a clean filter.

   Expect: Manifold on plate. Limit closed when cool.

Rod sees flame with the solenoid de-energized.

1. 1 Shut the gas cock first

   On Goodman GR9S96 the rod sees flame with the valve de-energized. Shut the cock. If flame stays, the valve is leaking — replace it. Do not jump or energize it as a test. Shut the gas cock. If flame stays, leaking valve — replace, do not jump.

   Expect: Flame dies when the cock is shut.

   If fail: Leaking valve. Replace. Do not leave the unit.

2. 2 Rod and IFC flame circuit

   If flame dies with the cock shut, the rod is shorted to ground or the IFC flame circuit is lying. Unplug the rod, inspect ceramic, and check the harness for a rub-through on the collector.

   Expect: Rod isolated from ground. IFC does not report flame with the rod unplugged.

3. 3 Confirm valve solenoids are actually off

   Measure 24 VAC at both solenoids after the call drops. A welded IFC relay or a shorted W will keep a solenoid wet and look like ‘unexpected flame.’ Replace the IFC only after the valve and rod are proven.

   Expect: 0 VAC at both solenoids after the call. No flame.

24 V fuse on the IFC is open.

1. 1 Find the 24 V short before you replace the fuse

   On Goodman GR9S96 an open IFC fuse is a short on W, Y, G, HUM, EAC, or a data pair landed on 24 V. Unplug the thermostat / data harness first. Short on W, Y, G, humidifier, EAC.

   Expect: Fuse out. 24 V transformer still good. Harness isolated.

2. 2 Replace the fuse with the harness off

   New fuse, harness still off. If it holds, the short is in the field wiring or accessory. Plug one circuit back at a time (W, then Y, then HUM/EAC). Unplug the tstat harness and replace the fuse.

   Expect: Fuse holds with harness off. Dies when the shorted lead lands.

3. 3 If it blows with the harness off

   Short is on the Goodman GR9S96 IFC or the gas-valve harness. Unplug the valve and try once more. Repeat blow with valve unplugged = IFC.

   Expect: Do not keep feeding fuses into a welded valve coil or a burned IFC trace.

Flame present, µA below threshold.

1. 1 Measure µA while it is running

   Do not clean first and guess. Series-µA the rod on Goodman GR9S96 during a call. Falling µA is oxide, ground, or a dying flame. A hard drop is often the pressure switch or limit opening, not the rod. Clean rod with a non-scratch pad.

   Expect: Flame rod: µA per this door card — not the GMSS96 flash sticker.

2. 2 Rod, ground, then gas

   Clean the rod with a non-scratch pad — not sandpaper. Chassis ground to burner box and IFC (painted screw and missing star washer are classic). Then manifold on the stage that is dropping and confirm LP conversion leftovers. Chassis ground, manifold, LP conversion.

   Expect: Manifold on the rating plate. Solid burner-box ground.

3. 3 Prove it is not a switch opening

   Watch the live Goodman GR9S96 display when flame drops. A PS or limit code that appears at the drop means the rod was a victim. Inducer, hose, vent wind, or a limit on a wrong heat tap.

   Expect: µA stable and the live code stays a flame code — then rod/valve/IFC. Otherwise chase the new code.

IFC did not see the igniter circuit behave as commanded.

1. 1 Ohms at the igniter, then at the IFC

   On Goodman GR9S96 measure cold ohms at the igniter plug, then at the IFC connector. An open at the plug is the element or local harness. Open only at the IFC is the harness rub-through on the collector. Igniter ohms cold, 120 VAC during warm-up, cracked nitride.

   Expect: Nitride cold ohms per THIS door sticker — do not use an 80% Norton chart.

2. 2 120 VAC during warm-up

   Call for heat and measure 120 VAC at the igniter during the warm-up window. 0 V + good ohms = IFC igniter relay. Voltage + no glow = cracked nitride.

   Expect: 120 VAC only during warm-up. Visible glow before the valve opens.

3. 3 Do not keep cycling a cracked element

   A cracked nitride can ohm ‘good’ cold and open hot. If ohms and voltage are good and there is no glow, replace the igniter. Confirm polarity/ground (this plate’s polarity code) before you condemn a new igniter.

   Expect: One clean light after a known-good igniter and a proven ground.

L1/N reversed or chassis ground missing.

1. 1 Hot and neutral at the IFC, not the disconnect

   On Goodman GR9S96 polarity/ground is measured at the board. A correctly landed disconnect with a swapped whip at the IFC still throws this. Hot and neutral at the IFC. Burner-box ground screw.

   Expect: L1 hot, N neutral, ~120 VAC L1 to N, ~0 VAC N to ground.

2. 2 Burner-box and IFC ground

   Green ground to cabinet and IFC. Painted screw and missing star washer fail the ground check and kill flame sense.

   Expect: Near-zero ohms burner box to IFC ground screw.

3. 3 Then flame and HSI

   Polarity/ground faults take out HSI and flame sense together. After the wiring is right, run one heat cycle and confirm µA and igniter glow before you change those parts.

   Expect: Code cleared. One clean light. µA in range.

Internal (EEb / ASME) or external (EEC) gas-valve electrical fault.

1. 1 Coil ohms and 24 VAC during trial only

   On Goodman GR9S96 measure each solenoid. 24 VAC should appear only during trial / the commanded stage. Valve coil ohms, 24 VAC at the harness during trial.

   Expect: Coil ohms per the valve sticker. 24 VAC only when the IFC commands that stage.

2. 2 Do not energize a leaking valve

   If the unexpected-flame code is also in history, shut the cock and replace the valve. Applying 24 V as a ‘test’ and walking away is a gas leak.

   Expect: No flame with the cock shut and solenoids de-energized.

3. 3 IFC relay vs the valve

   Voltage at the harness and a dead coil = valve. No voltage during a known trial = IFC relay or a lockout that never opened the valve (look at the live code).

   Expect: Known trial + 24 VAC + good coil = flame. Otherwise IFC.

Display is E 1 1 — not EE1 (PS closed). Manual-reset rollout. Treat as flame outside the exchanger until proven otherwise.

1. 1 Treat this as flame outside the exchanger

   Do not reset the Goodman GR9S96 rollout and walk away. Write the code, kill the call, and look for flame at the burners, crossover, and vestibule before you do anything else.

   Expect: No flame outside the exchanger. Burners seated. Crossover lit.

   If pass: Still inspect secondary / flue / condensate before you reset.

2. 2 Secondary, condensate, and flue

   Blocked secondary, drowned collector, or a plugged flue pushes flame out the front. Pull the inducer/collector look, confirm the trap is flowing, and check PVC/vent. Primary exchanger, burner alignment, crossover, blocked secondary / condensate / flue. Reset only after the cause is fixed.

   Expect: Dry collector, open flue, trap clear.

3. 3 Reset only after the cause is fixed

   Manual-reset rollout. Recurring rollout on Goodman GR9S96 is a CO / fire call — cracked primary, misaligned burners, or a failed secondary. Confirm CO in the space before you leave.

   Expect: One clean cycle after the cause is fixed. No second reset as a repair.

Igniter circuit measures open.

1. 1 Ohms at the igniter, then at the IFC

   On Goodman GR9S96 measure cold ohms at the igniter plug, then at the IFC connector. An open at the plug is the element or local harness. Open only at the IFC is the harness rub-through on the collector. Ohms at the igniter plug, then at the IFC.

   Expect: Nitride cold ohms per THIS door sticker — do not use an 80% Norton chart.

2. 2 120 VAC during warm-up

   Call for heat and measure 120 VAC at the igniter during the warm-up window. 0 V + good ohms = IFC igniter relay. Voltage + no glow = cracked nitride. Harness rub-through on the collector.

   Expect: 120 VAC only during warm-up. Visible glow before the valve opens.

3. 3 Do not keep cycling a cracked element

   A cracked nitride can ohm ‘good’ cold and open hot. If ohms and voltage are good and there is no glow, replace the igniter. Confirm polarity/ground (this plate’s polarity code) before you condemn a new igniter.

   Expect: One clean light after a known-good igniter and a proven ground.

Twinning miswire or twin terminal active on a standalone unit.

1. 1 Is this cabinet actually twinned?

   On a standalone Goodman GR9S96, nothing belongs on the TWIN terminal. A leftover jumper throws this. If not twinned, nothing should be on the TWIN terminal.

   Expect: TWIN empty on a single cabinet.

2. 2 Twinned pair must be the same IFC family

   Twinned units must be the same family and IFC revision. Mixing this plate with a communicating sister SKU will not twin.

   Expect: Same model family, same IFC, kit installed per the twinning sheet.

3. 3 Phasing and 24 V

   Twinning errors that survive a correct kit are 24 V phasing or a broken twin lead. Measure both cabinets before you change an IFC.

   Expect: In-phase 24 V. Continuous twin lead.

IFC failed its ground check (sister to EEA).

1. 1 Hot and neutral at the IFC, not the disconnect

   On Goodman GR9S96 polarity/ground is measured at the board. A correctly landed disconnect with a swapped whip at the IFC still throws this. Green ground to cabinet and IFC. Painted screw, missing star washer.

   Expect: L1 hot, N neutral, ~120 VAC L1 to N, ~0 VAC N to ground.

2. 2 Burner-box and IFC ground

   Green ground to cabinet and IFC. Painted screw and missing star washer fail the ground check and kill flame sense.

   Expect: Near-zero ohms burner box to IFC ground screw.

3. 3 Then flame and HSI

   Polarity/ground faults take out HSI and flame sense together. After the wiring is right, run one heat cycle and confirm µA and igniter glow before you change those parts.

   Expect: Code cleared. One clean light. µA in range.

9-speed ECM current too low (EbL) or unexpected (EbU).

1. 1 Is the wheel free?

   Spin the Goodman GR9S96 blower by hand. Ice, debris, or a seized bearing is not a control problem. Confirm the motor type on this plate — serial ECM, 9-speed tap, or X-13 — before you grab a capacitor. Harness seated at motor and IFC. A half-seated tap plug throws these.

   Expect: Wheel free. Correct motor family for this IFC.

2. 2 Command vs rotation

   Call for G or heat and confirm the IFC is actually requesting CFM (taps, serial, or communicating). Amp the motor. Locked rotor + a good command = motor. No command = IFC / harness / shared data. Locked rotor, wet winding, or a PSC motor someone hung on this IFC.

   Expect: 9-speed heat tap: Match the installer’s tap to the rise range on the rating plate (typically 35–65°F).

3. 3 Static and the wrong motor

   High static will trip current/limit codes and look like a dead motor. Measure TES vs this cabinet. Wrong horsepower or a leftover memory card after a control swap is the other half of this call.

   Expect: Static on the blower chart. Matching motor / shared-data card.

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

1. 1 Confirm this pair is actually A2L

   On Goodman GR9S96 FE3 / LE4 / SE5 / rE6-class codes are only valid when this furnace is tied to an R-32 or R-454B outdoor. On R-410A this is a miswired mitigation harness — not a leaking indoor coil.

   Expect: Outdoor refrigerant from the outdoor nameplate, not from memory.

   If fail: Remove / correct the mitigation harness. Do not condemn the IFC.

2. 2 Sensor location and the mitigation blower

   If it is a real A2L pair, follow the OEM mitigation sequence: sensor location, ventilation blower, relay. Only valid on A2L pairs. On 410A this is a miswired mitigation harness.

   Expect: Sensor seated where the I/O shows. Mitigation blower runs on a test.

3. 3 Do not bypass mitigation

   Never jump an A2L alarm to get heat. Find the leak or the failed sensor. Recurring mitigation with a clean sensor is a refrigerant leak until proven otherwise.

   Expect: Alarm clears only after the leak/sensor is fixed.