FieldBench

Carrier

24SPA6

AC · Performance · single-stage · InteliSense

Carrier Performance single-stage air conditioner. Contactor + dual cap like 24ACC6, plus InteliSense on late boards. Still not Infinity and still not two-stage.

Not 24TPA7 (two-stage Y2). Not 24VNA6 (inverter). Not 24ACC6 Comfort (no InteliSense, different series). Not 26SPA6 / 26SCA5 (R-454B).

Walk this in Diagnose

This plate

Stages
Single-stage scroll · one Y
Control
24V Y. InteliSense when the installing dealer opted in
Refrigerant
R-410A

This board

Single-stage Performance — contactor + optional InteliSense

  • Same cap / contactor / HPS story as Comfort.
  • InteliSense is remote data. It does not add Y2 or an inverter.

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

24SPA6 vs 24ACC6

Both look like a single-stage Carrier box.

  1. Plate 24SPA = Performance. 24ACC / 24SCA / 26SCA = Comfort.
  2. Charge and cap checks are the same class. Do not invent a Y2.
  3. InteliSense present ≠ Infinity ABCD.

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

  • A tech who just left a 24TPA7 will hunt Y2 here. There isn’t one.

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