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Models
Tranefurnace

S9X2

S-series · two-stage · constant-torque · 96%

Trane/AS S9X2 two-stage 96% with a constant-torque (X-13 style) blower and an IFC that still uses tap/profile setup. Cheaper cousin of S9V2. Same 96% dual-pressure-switch physics. Do not use the S9V2 ‘no dip switch / VS menu’ playbook.

Not S9V2-VS (serial ECM, IFC CFM menu, no dips). Not S9X1 (single-stage, one PS, no W2 prove). Not XC95m. Not S8X2 (80% metal vent).

Diagnose this modelInstall notesBoard cross-refField wiring

AFUE

96% condensing · two-pipe PVC

Staging

Two-stage valve · two-speed inducer · two pressure switches

Blower

Constant-torque ECM (taps / profiles) — not S9V2 serial VS

Setup

Heat/cool taps and profiles on the IFC or motor — not a VS CFM menu

Display

IFC status/fault — confirm THIS door card; E2.1 is still retry lockout on many

Sister SKU

American Standard S9X2 — same IFC family

This board

S9X IFC · tap/profile setup

  • Airflow is tap/profile, not an S9V2 VS CFM menu. If there are no dips/taps and a 3-character menu, you are on S9V2.
  • Fault decimals may rhyme with S9V2. E2.1 is still retry lockout on many S9X2 door cards — still read THIS door card before you name any other decimal.
  • Two pressure proves still exist. Low-fire and high-fire are different hoses.
  • Do not copy S9V2 E3.1 / E3.3 / E4.1 titles onto this door unless THIS card prints them.

On-board history if equipped. Write the full code before a power cycle.

Universal swap

No universal

Current S9X2 IFC — no published universal. ICM2915 is D674713P01 spark, not this nitride S-series card.

Silk: D674713P01

White-Rodgers

—

ICM

—

Honeywell

—
  • 50A55-843. ICM2915 ‘because two-stage Trane’. S9V2 VS board. ComfortLink.

After you pull the dead card

  1. 1OEM S9X2 IFC. Tap/profile setup is on that door — a PSC universal will not do it.

Field wiring

Written landings for Trane S9X2. Not a factory schematic.

Furnace · two-stage 24V
R / C / W1 / W2 / Y / GGas furnace

Two-stage conventional furnace. W1 low fire, W2 high fire. Outdoor staging is Y or Y1/Y2 — separate from the gas valve.

Written circuit description only — FieldBench does not redraw maker schematics. Example: R to W closes on a heat call; verify 24V at W1 before you change the IFC.

Open manufacturer PDF

Heat sequence

  1. 1Power. L1 / N → IFC → R120V / 24V
  2. 2Low. W1 → inducer LOW → LPS → HSI → valve LOWFirst fire
  3. 3High. W2 → inducer HIGH → HPS → valve HIGHSecond solenoid
  4. 4Flame. Rod → IFCµA DC both stages
  5. 5Blow. IFC → heat blowerAfter flame

This indoor

S-series CT two-stage. Same W1/W2.

24V two-stage heat

Door has W1 and W2. Not Infinity. Not ComfortBridge.

Two-stage thermostat

A single-W stat never proves high fire. That is not a weak inducer.

  • R24V hot24V
  • CCommon24V
  • W1Low-fire heat24V
  • W2High-fire heat24V
  • Y / Y1Cool24V
  • Y2Outdoor high if the condenser is two-stage24V
  • GFan24V

Two-stage IFC

W2 is high fire. Do not tee the pressure-switch hoses because there are two stages.

  • RHot24V
  • CCommon to outdoor24V
  • W1Low fire24V
  • W2High fire24V
  • YCool out24V
  • GBlower / cool tap24V

Landing

  • 24VStat W1IFC W1

    Low fire

  • 24VStat W2IFC W2

    High fire. Missing W2 = stuck on low.

  • 24VStat YIFC Youtdoor Y

    Cool

  • 24VC throughout

    Common

IFC harness — two-stage heat

W1 then W2. Low-fire prove is not high-fire prove.

Transformer + fuse

Same 24V transformer as single-stage. Fuse still kills the whole strip.

  • L1 / N120VLine
  • XFMR24V to R24V
  • FUSEOn the IFC24V

24V safety chain

Door, limit, rollout. A limit trip is not an E9 / 32 pressure-switch story.

  • DOORInterlock24V
  • LIMITMain limit24V
  • ROLLOUTManual reset24V

Two-speed inducer + two pressure switches

W1 = inducer low + LPS. W2 = inducer high + HPS. Separate hoses. Do not tee.

  • IND LO120V low-speed inducerLine
  • IND HI120V high-speed inducerLine
  • LPSLow-fire prove24V
  • HPSHigh-fire prove24V
  • HOSESOne hose per switch. Never tee LPS and HPS24V

HSI + two-stage valve

Igniter 120V. Low solenoid on W1. Second solenoid on W2 after HPS closes.

  • HSI120V igniterLine
  • MV / LO24V low-fire solenoid24V
  • HV / HI24V high-fire solenoid24V
  • FLAMEµA DC on the rod24V

Constant-torque ECM

Tap / profile motor. Not serial VS. Not a PSC cap.

  • TAPSHeat / cool / adjust profiles on the IFC24V
  • COMMONMotor common back to the IFC24V

Landing

  • LineW1IFCinducer LOWLPS

    120V inducer, 24V prove

  • LineIFCHSIvalve LOW

    120V igniter, 24V low solenoid

  • 24VW2inducer HIGHHPSvalve HIGH

    Missing W2 = stuck on low

  • 24VFlame rodIFC

    µA DC

  • LineIFCheat blower

    After flame. Motor class on this plate.

Prove it

  • W1 then W2 at the IFC under a 2-heat call.
  • If it never stages, W2 is missing at the board — not a bad gas valve until that is proven.

Do not

  • Do not convert this to Infinity by landing W on a random terminal.
  • Do not apply AMVC / ARVT ComfortBridge menus or a memory card.

926T / 59TP6 / AR9T96 / GR9T96 / S9V2 / EL296E class. Same landing on 80% metal-vent cousins — the vent is not the wire.

Sequence

  1. 1

    W1

    Inducer low → first-stage PS prove → HSI → low-fire valve → flame → CT blower on the heat tap.

  2. 2

    W2

    Inducer high → second-stage prove → second solenoid. Two switches, two hoses.

  3. 3

    E2.1

    On many S9X2 doors this is still retry lockout (ignition tries exceeded). Confirm THIS card. Same watch-a-try as S9V2 — different blower after it runs.

  4. 4

    Limit

    Wrong heat tap on a CT motor is the usual overtemp. Not an S9V2 menu miss.

Faults on this IFC

Step 1, then 2, then 3. Expected reading and the fail branch sit under each check.

E2.1

Retry lockout (confirm this door)

lockout

On many S9X2 door cards: ignition tries exceeded on this heat call. Confirm the exact line on THIS card — do not invent a different title.

  1. 1 Watch one full try — do not reset

    Write the Trane S9X2 code. Watch inducer, HSI glow, valve click, flame, µA. The step that dies is the repair. Resetting only burns another try into a harder lockout. Watch a try: inducer, HSI, valve, flame. Which step dies?

    Expect: W1 → W2 → E2.1 → Limit

  2. 2 Gas and the valve

    Cock open, inlet pressure, then manifold on the stage that is failing vs the rating plate. 24 VAC at the valve during trial? Coil ohms? A valve that never opens looks like a ‘bad igniter’ if you did not watch the sequence. Gas, igniter, rod, ground.

    Expect: Inlet and manifold on the plate. 24 VAC only during trial.

  3. 3 Flame prove, then the lockout timer

    Glow + valve + no prove → rod, ground, or IFC sense. Prove then drop → µA / PS / limit. Soft lockouts on this family often auto-reset on a long clock — do not sit on resets. Then taps if it lights and limits after the blower comes on.

    Expect: Stable µA after light-off. No new PS/limit code.

PS open / closed

Dual pressure switch (door decimals)

lockout

Same 96% two-switch physics as S9V2. Open = will not prove at that stage. Closed/shorted = already made when it should be open. Use the decimals printed on THIS S9X2 door — do not import S9V2 E3.1/E3.3 titles unless this card prints them.

  1. 1 Unplug the switch with the inducer off

    On Trane S9X2 this code is the switch made when the inducer is not running. Unplug that switch only. Two hoses, two switches. A tee is a miswire.

    Expect: Code changes when the harness is open.

    If fail: Wrong switch, or the IFC input is shorted.

    If pass: Switch/hose path. Go to step 2.

  2. 2 Water in the hose vs a welded switch

    Blow the hose. Water holding residual draft is more common than a welded switch. Confirm the hose is not teed and not routed uphill. Ohm the switch with the hose off. Trap, collector, PVC, wind, ice — 96% will not make pressure with a full trap.

    Expect: Hose empty. Switch opens with no draft.

  3. 3 IFC input last

    If the switch ohms open, the hose is dry, and the code does not change with the harness off, the Trane S9X2 IFC input is shorted. Do not keep swapping switches. Does the inducer actually change speed on W2?

    Expect: Known-good open switch + open harness = code gone. If not, IFC.

Limit

Open limit

warn

Overtemp / airflow. Wrong heat tap on a CT motor is the usual.

  1. 1 Airflow before you touch the limit

    On Trane S9X2 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). Heat tap vs rise range on the S9X2 chart — not the S9V2 menu.

    Expect: Rise in the rating-plate window. Static vs this cabinet’s blower chart.

  2. 2 Measure static and temperature rise

    Total external static vs the Trane S9X2 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, return, wheel.

    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). Rollout is a different switch — inspect exchanger before you reset.

    Expect: Manifold on plate. Limit closed when cool.

Polarity / power

Line / ground (door-card confirm)

lockout

If this door shows an E1-family or polarity code, treat it as L1/N / ground. Confirm the exact token on THIS card.

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

    On Trane S9X2 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.

    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. Door switch, 24 V secondary, chassis ground.

    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.

Workflows

Someone put an S9V2 motor in it

No heat after a motor change, or the blower never matches the taps.

  1. 1 Prove the call and the live code

    S9V2 VS motor will not run correctly on S9X2 taps.

    Expect: Write whatever S9X IFC · tap/profile setup is showing. On-board history if equipped. Write the full code before a power cycle.

    If fail: No call at the IFC → stat / harness. Do not change gas parts.

  2. 2 Isolate the first failed step in the sequence

    Match the motor to the model: S9X2 = constant torque.

    Expect: W2: Inducer high → second-stage prove → second solenoid. Two switches, two hoses.

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

    Then set heat/cool taps to the S9X2 chart, not the S9V2 menu.

    Expect: Motor: Tap/common 24V or OEM CT plug — not S9V2 serial VS. · Taps: Heat and cool match the S9X2 door chart for this cabinet / coil.

    If fail: Stay on this plate. The out-of-range reading is the part.

    If pass: Reading in range → the next step in this workflow is the repair.

Tap / profile setup

Limit trips, noisy returns, or ‘I set it like an S9V2.’

  1. 1 Prove the call and the live code

    There is no VS CFM menu on this IFC. Heat and cool are taps/profiles.

    Expect: Write whatever S9X IFC · tap/profile setup is showing. On-board history if equipped. Write the full code before a power cycle.

    If fail: No call at the IFC → stat / harness. Do not change gas parts.

  2. 2 Isolate the first failed step in the sequence

    Read the S9X2 tap chart for this cabinet and coil tons. Wrong heat tap is the winter callback.

    Expect: W2: Inducer high → second-stage prove → second solenoid. Two switches, two hoses.

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

    If the last tech ‘went into the menu and set CFM,’ they were on an S9V2. Re-set this one from the door chart.

    Expect: Motor: Tap/common 24V or OEM CT plug — not S9V2 serial VS. · Taps: Heat and cool match the S9X2 door chart for this cabinet / coil.

    If fail: Stay on this plate. The out-of-range reading is the part.

    If pass: Reading in range → the next step in this workflow is the repair.

96% dual-PS no heat / no high fire

Inducer runs, no light, or stuck on low.

  1. 1 Prove the call and the live code

    Same collector/trap physics as S9V2. Dump and prime the trap before you throw a switch.

    Expect: Write whatever S9X IFC · tap/profile setup is showing. On-board history if equipped. Write the full code before a power cycle.

    If fail: No call at the IFC → stat / harness. Do not change gas parts.

  2. 2 Isolate the first failed step in the sequence

    Low-only fail = first-stage hose/switch/inducer low. High-only fail = second-stage pair and whether the inducer actually went high.

    Expect: W2: Inducer high → second-stage prove → second solenoid. Two switches, two hoses.

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

    E2.1 after a failed prove is still retries — watch a try; do not start at the igniter if it never proved draft.

    Expect: Motor: Tap/common 24V or OEM CT plug — not S9V2 serial VS. · Taps: Heat and cool match the S9X2 door chart for this cabinet / coil.

    If fail: Stay on this plate. The out-of-range reading is the part.

    If pass: Reading in range → the next step in this workflow is the repair.

Test points

Motor

Tap/common 24V or OEM CT plug — not S9V2 serial VS.

Taps

Heat and cool match the S9X2 door chart for this cabinet / coil.

PS pair

Two switches, two hoses. Unplug test if the door shows a shorted/open decimal.

Display

Full token. E2.1 on many doors = retry lockout. Confirm any other decimal here.

Gotchas

  • S9X1 is the single-stage sibling — one PS, no W2 prove. Do not look for a second hose.
  • S9V2 looks the same in the basement and has no dips. Wrong playbook, wrong motor.
  • E2.1 here is still not Amana E2.
  • Do not import S9V2 E3.1 / E3.3 / E4.1 titles unless THIS S9X2 door prints them.

Related plates

Install this plate

Install S9X2 as two-stage 96% constant-torque. Tap/profile — not the S9V2 VS menu.

Cat IV PVC · two-stage · dual PS · CT / tap motor · 24V

Motor vs vent

  • Heat/cool taps or CT profiles. Do not look for the S9V2 CFM menu.
  • Same PVC dual-PS physics as S9V2. Prime the trap. Two hoses.

First fire

  1. 1Set the heat tap/profile for this cabinet, then W1/W2.
  2. 2Rise is tap-limited. Wrong tap = limit trip, not a VS calibration.

Do not on Trane S9X2

  • Do not steal S9V2 serial-ECM setup.
  • Do not apply S9X1 one-PS commissioning.

Maker literature

FieldBench does not host manufacturer files. Each link opens the maker’s own literature page in a new tab.

  • S9X2 product pageProduct pageTrane listing may show the restyled name; this was S9X2.Open manufacturer PDF
  • Trane residential furnacesProduct pageCurrent S-series / XC listing. S9X2 / S9X1 / S8X2 names have been restyled on this page.Open manufacturer PDF
  • Trane owner’s guidesOwner guidePublic owner manuals. Install / service literature lives in Trane e-Library (dealer).Open manufacturer PDF
  • Trane e-Library (public search)Literature searchSearch the plate (S9V2, S9X2, XV20i). Full I/O often needs a dealer login.Open manufacturer PDF
  • Trane e-Library searchLiterature searchSearch Trane S9X2 on the maker’s literature page.Open manufacturer PDF

Warranty and bulletins

Affected models, serial range, symptom, remedy, date. Maker files open on the manufacturer site.

All bulletins

  • Residential limited warranty

    warranty sheet

    Trane furnace warranty hub

    Registered residential furnace warranty · Limited warranty certificate

    Open factsOpen manufacturer PDF

  • Dealer portals

    dealer

    Where remaining service letters live

    Current-year service letters not on a public literature page · Maker dealer portal

    Open factsOpen manufacturer PDF