FieldBench
Models
Amanaac

ALXT7C

R-32 two-stage scroll

Amana R-32 two-stage condensing unit. Badge twin of Goodman GLXT7C. Not ASXC18 410A and not AXV9S inverter.

Not ASXC18 (R-410A two-stage). Not ALXS4B (R-32 single-stage). Not AXV9S.

Diagnose this modelInstall notesBoard cross-refField wiring

Refrigerant

R-32 (A2L)

Stages

Two-stage · Y1/Y2

Sister SKU

Goodman GLXT7C

This board

Two-stage outdoor · R-32

  • Outdoor board, not AMVC E-codes.
  • R-32 nameplate.

Outdoor LED before disconnect.

Universal swap

No universal

Amana ALXT7C outdoor. No furnace IFC universal. Replace the OEM outdoor control / contactor / drive by the silk.

Silk: ALXT7C

White-Rodgers

—

ICM

—

Honeywell

—
  • Indoor furnace universals (50A55, 50M56U, ICM282B, ICM2811, S9200U). This is not an IFC.
  • Do not ‘adapt’ a furnace board to an outdoor inverter, defrost PCB, or contactor.

After you pull the dead card

  1. 1Photograph the outdoor silk. Indoor 50A55 / ICM282B / S9200U do not belong here.
  2. 2Contactor units: replace the contactor / cap / HPS — there is no universal outdoor board.
  3. 3Inverter / communicating outdoors: OEM drive only. There is no White-Rodgers or ICM outdoor universal.

Field wiring

Written landings for Amana ALXT7C. Not a factory schematic.

Two-stage 24V · Y1 / Y2
Conventional Y1 / Y2 / CR-32 · A2L

Two-stage scroll. High stage is Y2 at the outdoor. A single-stage stat never gets you there. Still not Infinity ABCD.

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

This indoor

Y1/Y2. Not ASXC18 410A comm.

24V two-stage

Outdoor has Y1 and Y2. Not an inverter drive.

Wall thermostat

Two-stage cool. A single-Y stat never pulls high.

  • R24V hot24V
  • C24V common24V
  • Y1Low-stage cool24V
  • Y2High-stage cool24V
  • GIndoor fan24V
  • WHeat. Stays at the indoor.24V

Indoor IFC / AHU

Y1 and Y2 both have to leave this cabinet on high.

  • RTransformer hot24V
  • CCommon — run it to the outdoor24V
  • Y1Low-stage in / out24V
  • Y2High-stage in / out24V
  • GBlower24V
  • W1Heat24V

Outdoor — Y1 / Y2

Low vs high is these two screws, not an inverter L-code.

  • Y1Low-stage request24V
  • Y2High-stage request24V
  • C24V common24V

Outdoor line

208/230 through the disconnect to the contactor line side.

  • L1LineLine
  • L2LineLine
  • GNDEquipment groundLine

Dual run capacitor

C / FAN / HERM on the can. An inverter outdoor does not have this part.

  • CCommon — both windingsCap
  • FANOutdoor fanCap
  • HERMCompressorCap

Landing

  • 24VIndoor Rstat R · C throughout

    ~24 VAC

  • 24VStat Y1indoor Y1outdoor Y1

    Low-stage coil / request

  • 24VStat Y2indoor Y2outdoor Y2

    High-stage. Missing Y2 = stuck on low.

  • LineL1 / L2disconnect

    208/230

Prove it

  • Y1 at the outdoor on a 1-cool call. Then Y2 on a 2-cool / staging call.
  • If Y2 never arrives, the outdoor is not weak — the stat, indoor IFC, or the Y2 wire is.

Do not

  • Do not hunt ABCD / L-codes. If you see an inverter, you are on 24VNA6 / 191VAN / XV18.
  • InteliSense ≠ Evolution ABCD.

Preferred / Performance / Elite two-stage land here. Bryant 187B Evolution two-stage does not — that one is ABCD.

Sequence

  1. 1

    Y1 / low

    Outdoor starts low capacity. Indoor blower on low/mid Cool tap (24V) or communicating CFM (ComfortBridge indoor).

  2. 2

    Y2 / high

    Second stage. Head and subcooling should rise into the OEM SC window.

  3. 3

    Communicating pair

    GMVC96 / AVPTC indoor requests capacity on the data pair. No conventional Y needed. A 24V GR9T96 on that same pair is a miswire.

Faults on this IFC

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

HPS

High pressure

lockout

Outdoor airflow, overcharge, or restriction opened the high-pressure switch.

  1. 1 Heat rejection first

    On Amana ALXT7C high pressure is outdoor airflow until proven otherwise. Fan running the right direction, coil clean, fins not folded, no recirc over a fence or through a garage. Outdoor fan running? Coil dirty, recirc, bent fins.

    Expect: OD fan on, coil clean, discharge air leaving the top/side freely.

  2. 2 Head, subcooling, and liquid line

    Liquid pressure and liquid-line temperature → SC. High head + high SC = overcharge or non-condensables. High head + low SC = restriction or a dying compressor. Do not add gas because suction is low. Subcooling vs indoor TXV sheet. Liquid-line drier / restriction.

    Expect: SC vs the metering device on this plate (TXV ≠ piston).

  3. 3 Restriction vs the switch

    Drier, liquid-line kink, TXV inlet screen, or a non-feed indoor coil will stack head. Ohm / jumper-test the HPS only as a momentary prove, then restore it. A switch that opens on a known-good charge and clean coil is the switch. Do not keep resetting HPS into a locked fan.

    Expect: HPS closed at a normal liquid pressure for this refrigerant and OD ambient.

LPS

Low pressure / freeze

lockout

Suction dropped out — charge, indoor airflow, or TXV.

  1. 1 Airflow and freeze before you add gas

    On Amana ALXT7C low pressure / freeze is indoor airflow or a starved coil until proven otherwise. Filter, blower, dirty A-coil, closed supplies. In heat mode, a iced outdoor coil is the same family. Indoor filter, blower, coil freeze. Do not add gas on a frozen coil.

    Expect: Indoor air moving. Coil not iced. OD coil clear in heat.

  2. 2 SH / SC after a thaw

    Thaw fully. Then SH and SC vs the metering device. Low charge ices a piston. A TXV stuck closed ices with high SH. A restriction downstream of the ports fakes a low-charge chart. TXV / restriction. Weigh-out if the history is a leak.

    Expect: SH/SC in range for this refrigerant and device after a stable 10-minute run.

  3. 3 Leak, TXV, then the LPS

    Weigh-in if the chart says undercharge. Soap / electronic leak on joints and the coil. LPS that opens on a known-good charge and a clear coil is the switch — momentary test only, then restore. Low ambient and wind can nuisance-trip LPS on a light load — still prove charge.

    Expect: Charge on the nameplate. LPS closed at a normal suction for this OD ambient.

Comm

Indoor/outdoor data

lockout

ComfortBridge data pair only. Invalid as a diagnosis on a 24V Y1/Y2 hookup.

  1. 1 Data pair, not 24 V

    On Amana ALXT7C indoor/outdoor comm is a data pair (AB, S1/S2, U, ComfortBridge, ComfortLink — whatever THIS plate uses). It is not a 24 V Y. Check polarity, continuity, and that nobody landed it on R/C. Data pair polarity and splices. This is not 24V Y.

    Expect: Pair continuous, not shorted to chassis, polarity per the diagram.

  2. 2 Power both ends, then the outdoor status

    Indoor transformer and outdoor control both alive. Read the outdoor LED / 7-seg. Water in the outdoor control is the usual dead-end after a storm. Indoor IFC family must be GMVC / AVPTC communicating. GR9T96 / GMEC96 / GMSS96 cannot be the ComfortBridge indoor.

    Expect: Both controls powered. Outdoor showing a comm or address state, not a blank board.

  3. 3 Address / bias, then the control

    Communicating plates need a matching indoor address and sometimes a terminating bias. Swap is last: known-good pair + power both ends + correct address. One master on the bus. Outdoor board power before you condemn the indoor IFC.

    Expect: Indoor sees the outdoor. No comm code after a power cycle.

Workflows

Stuck on low, ALXT7C

Y2 never arrives.

  1. 1 Prove the call and the live code

    Prove Y2 at the outdoor.

    Expect: Write whatever Two-stage outdoor · R-32 is showing. Outdoor LED before disconnect.

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

  2. 2 Isolate the first failed step in the sequence

    R-32 SC on the TXV indoor.

    Expect: Y2 / high: Second stage. Head and subcooling should rise into the OEM SC window.

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

    Not an ASXC18 410A chart.

    Expect: Charge: Nameplate + line-set adders. SC per indoor TXV sheet. · Y1 / Y2: 24V pair: both present on high stage. Communicating pair: data, not 24 VAC.

    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

Charge

Nameplate + line-set adders. SC per indoor TXV sheet.

Y1 / Y2

24V pair: both present on high stage. Communicating pair: data, not 24 VAC.

Outdoor board

LED/display before the disconnect. Codes die when you pull power.

Gotchas

  • Goodman GLXT7C is the twin.

Related plates

Install this plate

Install Amana ALXT7C as R-32 two-stage scroll.

R-32 two-stage scroll

This plate — not the sister SKU

  • Not ASXC18 (R-410A two-stage). Not ALXS4B (R-32 single-stage). Not AXV9S.
  • Goodman GLXT7C is the twin.

Control on this outdoor

  • Outdoor board, not AMVC E-codes.
  • R-32 nameplate.

Hardware

  • Refrigerant: R-32 (A2L)
  • Stages: Two-stage · Y1/Y2
  • Sister SKU: Goodman GLXT7C

First fire

  1. 1Prove Y2 at the outdoor.
  2. 2R-32 SC on the TXV indoor.
  3. 3Not an ASXC18 410A chart.

Do not on Amana ALXT7C

  • Not ASXC18 (R-410A two-stage). Not ALXS4B (R-32 single-stage). Not AXV9S.
  • Goodman GLXT7C is the twin.

Maker literature

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

  • Amana literature libraryLiterature searchGas furnace / air-handler PDFs. Match the plate, not just the Amana badge.Open manufacturer PDF

Warranty and bulletins

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

All bulletins

  • Standard limited warranty

    warranty sheet

    Amana furnace heat-exchanger / unit-replacement terms

    Registered residential furnace warranty terms · 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