FieldBench

Carrier

25VNA4

Heat pump · Infinity Greenspeed inverter HP

Infinity inverter heat pump. Outdoor drive + ABCD. Faults are inverter/comm/sensor, not a contactor-and-cap story. Do not charge it like a 24ACC6 piston unit and do not look for L-codes on a Comfort single-stage.

Not 24VNA6 / 24VNA9 (AC-only inverter — no RV, no defrost). Not 25HBC / 24ACC6 / 24ABB3 / 24ACC4 single-stage (contactor, dual cap, piston/TXV). Not Performance 24TPA. A 24ACC6 has no inverter L-codes and no ABCD drive.

Walk this in Diagnose

This plate

Drive
Inverter scroll · variable capacity
Bus
Infinity ABCD to the wall control and indoor
Charge
Weigh-in + line-set. Superheat is not a 410A piston chart.
Sister
Bryant 280ANV · 24VNA6 AC-only inverter cousin

This board

Outdoor inverter + Infinity UI

  • Infinity thermostat events first — English text on the wall control.
  • Outdoor board / inverter LED for drive faults (overcurrent, discharge, comm). L5/L4-class on the drive, not a Comfort contactor chatter.
  • No conventional Y1/Y2 staging — capacity is serial. There is no outdoor contactor to listen for.
  • Do not apply a 24ACC6 dual-cap / SH-SC playbook as the first move.

Sequence

  1. Call. Wall control requests capacity over ABCD. Indoor IFC (59MN7 family typical) sets CFM. Outdoor inverter ramps. No Y contactor pull-in.
  2. Defrost. Inverter + IFC coordinate. A failed outdoor coil sensor looks like ‘always iced’ or ‘never defrosts.’
  3. Protect. HPS/LPS still trip the drive. Charge mistakes show up here — you do not ‘top off’ a Greenspeed.

Faults on this IFC

  • Comm

    ABCD / outdoor drop

    lockout

    Drive or bus. Wall control loses the outdoor.

    • ABCD landing and polarity, outdoor board power, inverter comms harness.
    • C still required at the wall control.
    • Indoor must be Infinity-capable. A 24ACC6-style indoor pairing is the wrong mental model.
  • HPS / LPS

    Pressure protection

    lockout

    Still real on an inverter.

    • Coil, fan, charge by weigh-in — you do not ‘top off’ a Greenspeed.
    • Outdoor fan that is actually the inverter-driven fan, not a dual-cap PSC motor.
    • Do not use 24ACC6 piston superheat as the pass/fail.
  • Inverter

    Drive overcurrent / overheat

    lockout

    L5/L4-class faults on the drive.

    • Compressor to ground, heat sink, supply voltage. Weigh-in vs nameplate.
    • These L-codes do not exist on 24ACC6. If you are looking at a contactor, you are on the wrong outdoor.

Workflows

No cool, Infinity HP

Fan indoor, outdoor silent.

  1. Stat event list. If it is a bus fault, do not gauge up yet.
  2. Outdoor powered? Inverter LEDs? There is no contactor chatter to chase — if you hear a contactor, it is not this unit (see 24ACC6).
  3. Charge is weigh-in plus line-set. Superheat on a variable drive is not a 410A piston chart and not a 24ACC6 TXV subcooling-only shortcut.
  4. Pair indoor must be Infinity (FE/FV/59MN7 family). A 59TP6 can sit on the same job only if the control scheme was designed for it — most were not.
  5. Do not replace a dual run cap that is not there.

Greenspeed vs Comfort 24ACC

Invoice just says Carrier heat pump.

  1. Inverter drive + ABCD = 25VNA / Greenspeed (this page). Contactor + dual run cap + piston/TXV = 24ACC6.
  2. No inverter L-codes on a 24ACC. No weigh-in-only-as-the-only-method on a piston 24ACC.
  3. Wrong charge method is how these get overcharged after a 24ACC tech treats them like a Comfort 13 SEER.

Test points

Charge
Recover and weigh. Nameplate + ounces/ft. Not piston SH.
ABCD
Communicating to the Infinity indoor / 59MN7 family. D is not Y.
Drive
Inverter LEDs / last fault. No contactor coil 24 VAC test.

Gotchas

  • Bryant 280ANV is the badge twin. 24VNA6 is the AC-only inverter cousin.
  • 24ACC6 is the Comfort single-stage cousin in name only — different everything.
  • 59MN7 is the indoor that belongs on this bus. 59SC5 / 24V Comfort pairing is not Greenspeed.

Related plates

  • bryant-280anv — Bryant Evolution Greenspeed factory twin. Type 280ANV on Diagnose.
  • carrier-59mn7 — Infinity modulating furnace — typical indoor on this ABCD bus.
  • carrier-24vna6 — Infinity inverter AC-only cousin — no RV, no defrost. Own chart.
  • carrier-24acc6 — Comfort single-stage AC — contactor + dual cap. Not this inverter.