FieldBench

Goodman

GLXT7C

AC · R-32 two-stage scroll · 17 SEER2 class

Current Goodman R-32 two-stage condensing unit. Y1/Y2 or communicating indoor depending on vintage. Not the R-410A GSXC18 and not the GXV9S inverter.

Not GSXC18 (R-410A two-stage / ComfortBridge). Not GLXS4B (R-32 single-stage, one contactor). Not GXV9S / GSXV9 inverter.

Maker PDFs

Walk this in Diagnose

This plate

Refrigerant
R-32 (A2L)
Stages
Two-stage scroll · Y1 low / Y2 high
Metering
TXV indoor required for rating
Pair
24V Y1/Y2 or communicating indoor per the outdoor diagram
Sister SKU
Amana ALXT7C

This board

Two-stage outdoor control · R-32

  • Codes are on the outdoor board. Indoor E-codes are the furnace.
  • Low vs high is Y1/Y2 or the communicating request — confirm which this vintage actually landed.
  • R-32 nameplate. Do not apply a GSXC18 410A SC target.

Sequence

  1. Y1 / low. Outdoor starts low capacity. Indoor blower on low/mid Cool tap (24V) or communicating CFM (ComfortBridge indoor).
  2. Y2 / high. Second stage. Head and subcooling should rise into the OEM SC window.
  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

  • HPS

    High pressure

    lockout

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

    • Outdoor fan running? Coil dirty, recirc, bent fins.
    • Subcooling vs indoor TXV sheet. Liquid-line drier / restriction.
    • Do not keep resetting HPS into a locked fan.
  • LPS

    Low pressure / freeze

    lockout

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

    • Indoor filter, blower, coil freeze. Do not add gas on a frozen coil.
    • TXV / restriction. Weigh-out if the history is a leak.
    • Low ambient and wind can nuisance-trip LPS on a light load — still prove charge.
  • Comm

    Indoor/outdoor data

    lockout

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

    • Data pair polarity and splices. This is not 24V Y.
    • Indoor IFC family must be GMVC / AVPTC communicating. GR9T96 / GMEC96 / GMSS96 cannot be the ComfortBridge indoor.
    • One master on the bus. Outdoor board power before you condemn the indoor IFC.

Workflows

No cool or stuck on low, GLXT7C

Runs on Y1 only, or silent.

  1. Prove Y1 and Y2 at the outdoor under a high-stage call. A leftover single-stage stat will never pull high.
  2. R-32 pressures and SC on the TXV indoor. Not a GSX16 piston SH chart.
  3. If the indoor is ComfortBridge, confirm this outdoor actually talks. Many GLXT land 24V only.

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

  • GSXC18 in the same yard is 410A. Do not swap driers, pistons, or charge charts across refrigerants.
  • Amana ALXT7C is the badge twin.

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