FieldBench
Procedures
Electrical8 min

IFC board swap

Photograph the silk. Match staging, igniter, and motor class. A 50A55 does not run ComfortBridge or a 9-speed tap.

Before you order

  • The furnace model is not the board. Photograph the silk-screen part number on the dead IFC (PCBBF132, HK42FZ017, 107045-03, 62-24084-82).
  • Match three things: staging (1 / 2 / modulating), igniter (carbide 120 V, nitride 80 V, or spark), and motor (PSC, ECMx, 9-speed tap, or serial communicating VS).
  • Open the Board cross-ref in FieldBench and type that silk or the cabinet model. ComfortBridge, Infinity, Evolution, iComfort, ComfortLink, EcoNet, and Daikin One have no White-Rodgers, ICM, or Honeywell universal.

Cartons that are actually universal

  • 50A55-843: single-stage silicon-carbide HSI, PSC relay. Replaces most 50A50/50A55. Not nitride, not two-stage, not 9-speed tap.
  • 50A65-843: single-stage 80 V nitride — keep the igniter. Still PSC, still single-stage.
  • 50M56U-843 / ICM2812-KIT: single-stage carbide or nitride (kit includes 21D64-2 HotRod). Carrier list is HK42FZ004/007/008/009/011/016 — not 013, not an 11-pin bar.
  • 50M56X-843: newer single-stage for PSC and ECMx. Still not a 9-speed tap card and not communicating.
  • Honeywell/Resideo S9200U1000: single-stage 120 V HSI IFC, PSC circulator. list includes B18099-06/08/10/13, 102077-xx, ICM280, 50A55-843, older York 031- / Trane CNT. Not HK42FZ, not PCBBF132/136, not ComfortBridge.
  • Honeywell ST9120U1011 is a fan timer (ST9101/20/41/60). S8610U3009 is intermittent pilot. S8910U1000 is an HSI module only (S89 / 50E47 / HS780). None of those three replace an integrated IFC.
  • ICM282B: Carrier HK42FZ004–016/034 including 013. ICM2807 is HK42FZ017 two-stage only.
  • ICM2811: Goodman PCBBF110/112/123 / B18099-26. ICM2810: PCBBF136/140 only. 50M56-743: PCBBF132 (AR9T96 / GR9T96).

After the new card is in

  • Set heat-off delay and any 80+/90+ jumper to the door card. Use the lettered harness the kit sheet names — do not guess a plug.
  • Prove flame µA, clock the meter, and run every stage the door lists. Two-stage: low-fire PS then high-fire PS, hoses not teed.
  • Wrong board can skip a pressure switch or limit. Treat a bad swap as a CO / fire call.