FieldBench

Amana

ASXC18

AC · Two-stage / communicating outdoor · 18 SEER class

Amana-badge two-stage communicating condensing unit. Same outdoor family as Goodman GSXC18. Codes are on the outdoor board. ComfortBridge indoor (AMVC / AVPTC) or 24V Y1/Y2.

Not ASX16 (single-stage contactor). Not AXV9S inverter. Not ASZC18 heat pump. Not ALXT7C (R-32 two-stage).

Walk this in Diagnose

This plate

Stages
Two-stage scroll
Refrigerant
R-410A on this generation
Pair
ComfortBridge AMVC / AVPTC or 24V Y1/Y2
Sister SKU
Goodman GSXC18 · AVXC20

This board

Outdoor communicating control (Amana badge)

  • Outdoor board, not the AMVC96 E-codes.
  • Comm faults are invalid on a 24V AR9T96 / AR9S96 hookup — land Y1/Y2.

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, ASXC18 + AR9T96 indoor

Mixed 24V Amana 9-speed indoor + two-stage outdoor.

  1. This pair is 24V Y1/Y2. No ComfortBridge indoor menus.
  2. Y1 then Y2 at the outdoor. Charge by SC on the TXV coil.
  3. Data wire to an AR9T96 is a miswire.

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 GSXC18 is the factory twin. Same outdoor board family.
  • ASZC18 adds the RV and defrost — different chart.

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