Nameplate R-454B. 24SPA6 410A ounces are the wrong book.
Sequence
Y. Indoor stat Y → 24 VAC across outdoor C and contactor coil. Contactor pulls in → compressor + outdoor fan on the dual cap.
HPS. High-pressure switch opening drops the coil. Contactor drops. No inverter alarm, just silence or chatter.
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
26SPA6 no-cool / charge
New Performance 16, or a 410A tank on the truck.
24 VAC at the contactor, dual cap, then R-454B SH or SC.
InteliSense present ≠ Infinity and ≠ Y2.
Do not top off 410A.
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
26SCA5 is the Comfort badge next to this one. Same refrigerant, fewer options.