FieldBench

Goodman

GMVC96

Furnace · ComfortBridge · variable-speed · two-stage · 96% AFUE

Goodman ComfortBridge communicating 96% two-stage. Triple 7-segment IFC, 14-pin serial ECM, optional communicating thermostat with 24V fallback. Badge twin of Amana AMVC96. Dual pressure switches still exist — the display language is ComfortBridge E/b/d, not a 9-speed tap card.

Not GR9T96 / GD9T96 (single 7-seg E0–E9, 9-speed tap motor, conventional 24V only). Not GMEC96 (constant-torque / X-13, no ComfortBridge serial). Not GMSS96 (single-stage LED flash). Not GMVM97 (modulating valve — percent capacity, not two-stage Ht1/Ht2).

Maker PDFs

Walk this in Diagnose

This plate

Input / AFUE
Up to 96% · two-stage heat
Staging
Two-stage valve · two-speed inducer · dual pressure switches
Blower
Communicating variable-speed ECM (14-pin serial, CFM requested, not taps)
Control
ComfortBridge IFC · triple 7-segment + menu buttons
Tstat
ComfortBridge / communicating preferred · 24V W1/W2 fallback
Shared data
Memory card on the IFC stores cabinet size / motor tables — move it with the board
Sister SKU
Amana AMVC96 · GMVM97 is the modulating cousin

This board

ComfortBridge IFC · three 7-segment digits + menu buttons

  • Three digits, not one. Status words (idle, Ht1, Ht2, CF, CL1) are not faults.
  • Faults are letter+digit: E0–E9 / EA / EE for heat/prove, b0–b9 for the serial ECM, d0/d4 for the shared-data card.
  • Learn / menu buttons step through CFM, heat staging, and last faults. Do not treat a setup screen as a lockout.
  • Read the door card on THIS revision — ComfortBridge menus moved between board generations.
  • A communicating outdoor on the same bus changes what a ‘no Y’ complaint means — the IFC may be the thermostat.

Sequence

  1. Call. Communicating tstat requests heat capacity. On 24V fallback, W1/W2 behave like a two-stage furnace but CFM still comes from the IFC tables — there are no heat taps.
  2. Inducer / low PS. Inducer on low. Low-fire PS must close. Already closed with inducer off → E1. Never closes → E2. Same physics as GR9T96, ComfortBridge presentation.
  3. HSI / low-fire valve. Nitride warm-up, first-stage solenoid. Failures stack to E0 after 3 retries. Open igniter / ground → E7.
  4. Blower. Serial ECM ramps to the IFC heat CFM. A tap jumper from a GR9T96 or a CT plug from a GMEC96 will not run this motor.
  5. W2 / high fire. Inducer goes high (or the communicating request raises capacity). High-fire PS must close (E9 if open, E8 if it was already closed). Second solenoid opens.
  6. Satisfied. Valve off, post-purge, blower delay. Unexpected flame → E4.

Faults on this IFC

  • idle / Ht1 / Ht2 / CF / CL1

    Status, not a fault

    info

    Normal run states on the triple display. idle = standby, Ht1/Ht2 = low/high heat, CF = continuous fan, CL1 = low cool.

    • Do not replace the board because it says Ht1 or idle.
    • CF is continuous-fan CFM, not a capacitor.
    • Ht1 forever with a high-stage request → staging / E8–E9 path, not a ‘bad Ht1 code.’
  • E0

    Retry lockout (3 retries)

    lockout

    Ignition or recycle limit on this call. Three failed tries and the IFC sits.

    • Watch one full try: inducer, HSI, valve, flame, µA. Which step dies?
    • Gas supply and manifold low then high.
    • Do not keep resetting the hour — find the failed step.
  • E1

    Low-fire PS stuck closed

    lockout

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

    • Unplug the LPS. Code change = welded switch or water in the hose.
    • Same collector-hose physics as GR9T96 E1. Communicating does not fix a drowned trap.
  • E2

    Low-fire PS open

    lockout

    Inducer on low, low-fire switch will not close.

    • Inducer 120 VAC and spinning on the heat call.
    • Trap, collector, PVC intake/exhaust, LPS hose on the low tap.
    • Shared-data / CFM settings do not create draft. Fix the vent path.
  • E3

    Limit / rollout

    warn

    Primary limit or rollout string opened. VS motor should have been ramping — if the limit still opens, static or overfire. Rollout in this string is still a flame-containment hazard.

    • IFC heat CFM setting, not a 9-speed tap. Filter, coil, return size.
    • Which switch in the string is open? Limit = airflow. Rollout = exchanger / burners / flue — manual reset, treat as hazard.
    • Manifold vs plate. Overfire trips limits with a clean filter.
  • E4

    Unexpected flame

    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

    IFC automotive fuse is open.

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

    Low flame signal

    warn

    Flame present, µA below the IFC threshold.

    • Clean rod with a non-scratch pad.
    • Chassis ground to burner box and IFC.
    • Manifold / orifice / LP conversion.
  • E7

    Igniter / ground

    lockout

    Igniter circuit or flame-sense ground did not behave as commanded.

    • Igniter ohms cold and 120 VAC during warm-up.
    • Cracked nitride. Burner-box ground screw (paint, missing star washer).
    • Do not confuse with b0 — E7 is HSI/ground, b0 is the indoor blower.
  • E8

    High-fire PS stuck closed

    lockout

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

    • Second switch — do not treat as E1.
    • Welded HPS or water-filled hose.
    • W2 shorted to W1 on 24V fallback.
  • E9

    High-fire PS open

    lockout

    Inducer on high, high-fire switch never closes. Runs on low, will not go high.

    • Does the inducer actually change speed on the high-stage request?
    • HPS hose on the high tap only — never teed to the LPS.
    • Vent capacity on 100–120 kBtu cabinets. High fire needs more draft than E2 ever saw.
  • 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.
  • EE

    No 115V / internal

    lockout

    IFC lost line voltage or failed an internal power/self-check. This is not a ComfortBridge data-pair code.

    • L1/N at the IFC, door switch, incoming 120 VAC under load.
    • Transformer 24 VAC secondary. Internal IFC failure only after line power is proven.
    • Do not chase a data pair because an older note called EE ‘bus.’ On this chart EE is power/internal.
  • b0

    ECM not running

    lockout

    IFC commanded the serial blower and it did not run.

    • 14-pin harness fully seated at motor and IFC. No tap plugs on this motor.
    • Line voltage at the motor, wheel free, no water in the winding.
    • Wrong motor (9-speed or CT) in this cabinet will sit here forever.
  • b1

    ECM comms lost

    lockout

    Serial link between IFC and indoor blower dropped after the motor was seen.

    • Harness continuity and pin tension on the 14-pin. Rub-through at the blower deck.
    • Motor control module vs IFC — reseat both before you replace both.
    • This is motor serial, not the ComfortBridge thermostat data pair.
  • b2

    HP mismatch vs shared data

    lockout

    Motor horsepower does not match what the memory card / shared data says this cabinet is.

    • Compare motor HP stamp to the furnace model and the shared-data card.
    • After an IFC or motor swap, the card from the old board must travel with the cabinet size.
    • A ¾ HP motor in a 1 HP cabinet (or the reverse) throws b2 even when the wheel spins.
  • b3

    Motor limiting

    warn

    ECM is folding back current / torque — usually static, not a dead motor.

    • Total external static vs the GMVC96 blower chart. Media cabinet + dirty coil is the usual.
    • IFC cool/heat CFM set higher than the duct can take.
    • Wheel rub or restriction that is not quite a lock.
  • b4

    Trip / lost rotor

    lockout

    Motor tripped or lost rotor position while running.

    • Wheel interference, wet winding, failing module.
    • Line voltage sag at the motor during ramp.
    • Replace motor only after harness and static are clean.
  • b5

    Locked rotor

    lockout

    Blower cannot turn.

    • Spin the wheel by hand. Ice, debris, seized bearing.
    • Capacitor is not the play — this is a serial ECM.
  • b7

    Motor parameters

    lockout

    IFC rejected the motor’s reported parameters vs shared data.

    • Motor is the OEM serial ECM for this cabinet — not a ‘close’ aftermarket that talks a different table.
    • Shared-data card present and for this model family.
    • Reflash / card reseat before condemning a new motor.
  • b9

    Low airflow

    warn

    Delivered CFM well below the request. Duct or restriction, not an ignition code.

    • Filter, coil, closed returns, crushed flex.
    • IFC CFM vs actual TES. b3 often rides along.
    • Do not raise heat CFM into a brick to ‘fix’ b9.
  • d0

    No shared data / missing memory card

    lockout

    IFC cannot read the furnace identity card. Classic after an IFC swap when the card stayed on the old board or in the box.

    • Look at the small memory / shared-data card on the IFC. It must be present and seated.
    • Move the card from the failed IFC onto the replacement — that card is the cabinet.
    • A blank replacement board with no card will not run this furnace. Do not ‘program around it’ with GR9T96 taps.
  • d4

    Invalid memory card

    lockout

    Card is present but the data is corrupt, wrong family, or unreadable.

    • Card from a GMVM97, GMEC, or a different tonnage will read invalid on this IFC.
    • Reseat. If it still d4s, OEM card for this exact GMVC96 size — not a generic ‘ComfortBridge card.’
    • Do not mix Amana AMVM97 modulating cards into a two-stage GMVC96.

Workflows

Identify vs GR9T96

First minute on site. Data plate dirty or the last tech mixed boards.

  1. 14-pin serial motor plug + triple 7-seg with menu buttons = stay on GMVC96.
  2. Single 7-seg and a 9-speed tap harness (no 14-pin serial) = GR9T96. Leave this page.
  3. CT / X-13 style 5-wire profile plug, two-stage, 7-seg E0–E9, no ComfortBridge menu = GMEC96.
  4. One pressure switch and a flashing LED = GMSS96.
  5. Do not install a GR9T96 9-speed motor as a ‘cheaper ECM’ in this cabinet.

b0 / b1 motor

Heat or cool call, blower silent or dropping, b0 or b1 on the triple display.

  1. Photograph the three characters. b0 = never ran. b1 = ran and the serial link died.
  2. Reseat the 14-pin at motor and IFC. Look for rub-through at the blower rail.
  3. Line voltage at the motor. Wheel free? Water in the end bell?
  4. If a 9-speed or CT motor is in this housing, stop — that is the fault.
  5. b2/b7 after a motor change: HP and shared-data card must match the cabinet. The new motor is not ‘plug and play’ across sizes.
  6. Replace motor and IFC only after comms and static are proven. Do not shotgun both on the first visit.

d0 after IFC swap

New board, furnace will not configure, d0 or d4.

  1. The memory / shared-data card from the old IFC must move to the new one. That card is the furnace model.
  2. d0 = card missing. Look in the old board’s socket, the parts box, and the blower deck.
  3. d4 = card present but wrong family or corrupt. A GMVM97 or GMEC card will not satisfy a GMVC96.
  4. Power up only after the card is seated. Configuring without it teaches the next tech nothing.
  5. Then set CFM / staging in the menu. There are no heat taps to ‘get close enough.’

ComfortBridge bus vs 24V fallback

Stat shows a call, furnace idle — or the job was ‘converted’ off a communicating stat.

  1. Photograph the triple display and the stat error before touching wires.
  2. Is the IFC in communicating mode or 24V fallback? That changes every next step.
  3. Communicating: data pair polarity and splices. This is not 24 VAC. Only one master on the bus. Outdoor crashing the bus will idle the indoor.
  4. 24V fallback: W1/W2 at the IFC, then inducer / PS / HSI as a two-stage 96%. CFM still comes from IFC tables.
  5. Leftover data wires landed on R/C/W is a fuse (E5) or a dead call, not a bad serial motor.
  6. A GR9T96 indoor cannot be the ComfortBridge partner for a communicating outdoor. That pair is Y1/Y2.

Test points

Data pair
OEM communicating voltage / polarity — never 24 VAC between the data pins.
Motor harness
14-pin serial ECM, fully seated. No tap plugs. No CT profile harness.
Shared-data card
Seated on the IFC. Travels with the cabinet on a board swap.
LPS / HPS
Both NO. Closed only when that inducer speed is making the collector setpoint.
Flame rod
µA per this IFC sticker, not the GR9T96 door card.

Gotchas

  • Door cards differ by board generation. A 2014 GMVC96 card is wrong on a later triple-display replacement IFC.
  • GMVM97 looks identical in the basement and is modulating — two-stage staging tests will lie.
  • Amana AMVC96 is the badge twin. Same chart. GM9S96 / GMSS96 is not.
  • Warehouse ‘Goodman 96% IFC’ is often this board. It will not run a GR9T96 9-speed motor.
  • EE on this chart is no 115V / internal — not a ComfortBridge bus code. Diagnose line power first.

Related plates

  • amana-amvc96 — Amana badge twin — same ComfortBridge IFC family and serial ECM.
  • goodman-gmvm97 — Modulating ComfortBridge cousin. Same E/b/d language, percent valve, not Ht1/Ht2.
  • goodman-gr9t96 — 9-speed 24V twin-look. Single 7-seg, tap motor. Do not swap IFCs or motors.