FieldBench

Carrier

24ACC6

AC · Comfort · single-stage condensing unit

Carrier Comfort single-stage air conditioner. Contactor + dual run capacitor + piston or TXV indoor. Conventional 24V Y. Not Greenspeed, not Infinity 24VNA / 25VNA. There are no inverter L-codes on this outdoor.

Not 25VNA4 / 24VNA6 Greenspeed or Infinity inverter (ABCD drive, weigh-in, no contactor). Not 24TPA7 two-stage. Not 24ANB / Performance communicating. Not 26SCA5 / 26SPA6 (R-454B Comfort/Performance). 24ABB3 / 24ACC4 / 24SCA5 are Comfort single-stage cousins — same contactor-and-cap story, still not an inverter.

Walk this in Diagnose

This plate

Staging
Single-stage scroll or reciprocating · one contactor
Start components
Dual run capacitor (HERM + FAN). Hard-start only if the door/OEM calls for it
Metering
Piston or TXV at the indoor — read the coil / furnace pairing, not the outdoor badge
Control
24V Y/C to the contactor coil. No ABCD. No inverter.
Sister
24ABB3, 24ACC4, 24SCA5 Comfort single-stage

This board

No inverter board — contactor, cap, pressure switch

  • There is no two-digit IFC and no inverter L-codes. If you are reading L5/L4, you are on a 25VNA / 24VNA drive, not this unit.
  • High-pressure switch is in series with the contactor coil on typical Comfort wiring — open HPS = no pull-in.
  • Outdoor fan fail is a capacitor, motor, or mechanical bind — not an inverter fan module.
  • Charge: superheat if the indoor is piston, subcooling if the indoor is TXV. Do not default to Greenspeed weigh-in-only.

Sequence

  1. Y. Indoor stat Y → 24 VAC across outdoor C and contactor coil. Contactor pulls in → compressor + outdoor fan on the dual cap.
  2. HPS. High-pressure switch opening drops the coil. Contactor drops. No inverter alarm, just silence or chatter.
  3. Charge. Piston indoor: set by superheat. TXV indoor: set by subcooling. Rating-plate weigh-in is a starting point, not the Greenspeed-only method.

Faults on this IFC

  • HPS

    High pressure switch open

    lockout

    Outdoor HPS opened — coil circuit is dead. Not an inverter pressure fault and not an L-code.

    • HPS continuity, reset if manual, wiring in series with the coil.
    • Outdoor airflow: dirty coil, bent fins, fan not running (see ODF / cap).
    • Overcharge or non-condensables — confirm indoor metering before you recover (SH vs SC).
    • Do not treat this as a 25VNA drive trip.
  • ODF

    Outdoor fan fail

    warn

    Fan not turning. Compressor may still run and then HPS.

    • Dual-cap FAN section µF vs sticker. A good HERM and a dead FAN is the usual Comfort call.
    • Fan motor ohms / ground, blade clearance, capacitor wiring (C / FAN / HERM).
    • Not an inverter fan module — there isn’t one.
  • Contactor

    Contactor / coil

    warn

    Will not pull, chatters, or is welded.

    • 24 VAC at the coil under a Y call. Low voltage = long stat wire, weak indoor transformer, or a furnace 24 (fuse) problem.
    • Coil ohms / burned turns. Pitted or welded points — replace, do not file and leave.
    • Chatter: low 24V, bad coil, weak transformer — not an inverter ramp.
  • Cap

    Dual run capacitor

    warn

    HERM and/or FAN section out of rating. Single-stage Comfort dies this way all summer.

    • Both sections vs microfarad rating, not just one.
    • Bulged can, open bleed, wrong replacement (single vs dual, voltage).
    • Hard-start add-ons do not fix a dead FAN section.
  • Charge

    Charge (SH piston / SC TXV)

    warn

    Wrong charge method is as common as wrong charge.

    • Indoor piston: charge by superheat. Indoor TXV: charge by subcooling.
    • Do not use Greenspeed weigh-in-only as the only method unless the factory TXV rating plate on THIS outdoor says so. Most 24ACC are piston/TXV conventional.
    • Line-set length and indoor coil match still matter. Weigh-in after a repair, then finish on SH or SC.

Workflows

No-cool contactor chatter

Outdoor buzzes, pulls in and drops, or never stays in.

  1. Measure 24 VAC at the contactor coil under the Y call — at the outdoor, not just at the stat. Low 24V, bad coil, or weak indoor transformer are the chatter triad.
  2. Indoor 24 (fuse) / transformer VA. A 59SC5 or air handler with a loaded HUM/EAC and a long 18-ga run will chatter this Comfort contactor.
  3. Coil resistance and burned varnish. Replace a cooked coil; do not hold it in with a screwdriver.
  4. HPS in series: an opening switch looks like chatter. Clamp it only as a test, then find coil/airflow/charge.
  5. This is not a 25VNA inverter. There is no L-code and no drive to reset.

Charge: SH vs SC vs Greenspeed habit

After a repair, a low-capacity complaint, or a tech who just came off a 25VNA.

  1. Identify indoor metering. Piston (orifice) indoor → superheat. TXV indoor → subcooling.
  2. Do not stop at weigh-in-only unless THIS rating plate is a factory TXV unit that specifies weigh-in as the method. Most 24ACC Comfort units are conventional piston/TXV.
  3. Finish on gauges the conventional way. Greenspeed weigh-in-only is the 25VNA page, not this one.
  4. If HPS opened after a ‘top off,’ recover and start over — Comfort singles get overcharged when someone uses a 410A rule of thumb and walks.

Test points

Contactor coil
Stable ~24 VAC on Y. Chatter = voltage, coil, or HPS. No ABCD to probe.
Dual cap
HERM and FAN both within ~6% (or OEM) of the stamped µF.
Charge
SH target on piston indoor; SC target on TXV indoor. Weigh-in is a start, not a Greenspeed-only finish.
HPS
Closed at rest. Open under high head = airflow/charge, not an inverter L-code.

Gotchas

  • No inverter L-codes exist on this outdoor. If you see them, you are on 25VNA / 24VNA.
  • 24ABB3, 24ACC4, 24SCA5 are Comfort single-stage cousins — same chart.
  • Indoor pairing is often a 59SC5 / coil-piston or TXV. Charge method follows the indoor, not the 24ACC badge.
  • A hard-start kit does not replace a dual cap and does not turn this into a Greenspeed.

Related plates

  • carrier-25vna4 — Infinity Greenspeed inverter HP — no contactor, no dual cap, weigh-in. Opposite of this unit.
  • carrier-24vna6 — Infinity inverter AC. No contactor. Own chart.
  • carrier-24tpa7 — Performance two-stage. Y1/Y2.
  • carrier-24spa6 — Performance single-stage InteliSense.
  • carrier-26sca5 — R-454B Comfort single-stage successor.
  • carrier-59sc5 — Comfort 96 furnace often paired with this outdoor — 24V Y, piston or TXV indoor coil.