Read Carrier two-digit furnace codes
Three blinks, pause, one blink is 31 — not Goodman 3-flash. A VS display of 3 1.6 is often live CFM, not a fault. 33 hardens to 13; 34 hardens to 14. Bryant 926T speaks this chart; Infinity 31 is a pressure band.
How To stays open. Diagnose walks the next measurement.
Before you start
- 33 includes rollout. If the rollout is open, inspect the exchanger — do not keep resetting.
- 22 is flame with the valve off. Shut the cock.
- Do not jumper a pressure switch or limit to ‘see if it runs.’
On the truck
- Live IFC LED or 7-seg — do not kill power
- Phone for the door card (11–45 list)
- Rating plate: 59TP6 vs 59SC5 vs 59MN7 vs 58STA
Steps
1 Count two groups, not one
Carrier Comfort / Performance IFCs flash TWO digits. Count the first burst, wait the short pause, count the second. 3 then 1 = 31. 3 then 3 = 33. 3 then 4 = 34. A long pause, then the pair repeats. This is not a Goodman 1–9 single-count and not a rooftop IGC 3-flash.
Expect: A two-digit written down (31, 32, 33, 34, 13, 14…).
If it fails: One long even blink while it runs is heartbeat / run, not a code. Rapid polarity flash is a Goodman habit — not this IFC.
2 Fault vs CFM readout (3 1.6 is not 31)
On 59TP6 / 926T variable-speed boards a steady readout like 3 1.6 is often STAGE + CFM (stage 3 / 1,600 CFM). Faults flash the two-digit; run status sits still. Photograph the door. Comfort 59SC5 does not report staged CFM that way. Do not start a 31 trap job on a furnace that is happily blowing 1,600.
Expect: Flashing two-digit = fault. Steady 3 1.6-class display = airflow status.
If it fails: Already killed power? Live code is gone. Recall stores ~48 h (code 11 = empty history). Recreate the W call.
3 The winter four, then the lockouts
31 = inducer running, pressure switch did not close (draft). 32 = low-fire PS on two-stage (59TP6 / 926T / 59TN6) — on 59SC5 it is the only switch if the door lists it. 33 = limit or rollout open. 34 = ignition did not prove. Held 33 becomes lockout 13 (~3 h auto-reset). Three 34s become lockout 14. Fix the live 31/33/34; do not sit on 13/14 resets.
Expect: Live digit named, then the matching circuit (hose, rise, HSI) measured.
If it fails: 23 = the switch never reopened (welded / water in hose / inducer still spinning). 42 with 31 = inducer RPM out of band, not a new switch.
4 31 is draft — vent material is the repair
96% (59SC5, 59TP6, 59TN6): trap, collector, PVC slope, attic ice, wind. 80% Comfort (58STA class): chimney, liner, cap, common-vent — there is no 96% collector to dump. Infinity 59MN7 31/42 is an inducer/pressure BAND, not two discrete switches to ohm as low vs high.
Expect: Vent family named (PVC vs metal vs modulating band) before any part swap.
If it fails: Bryant 926T = 59TP6 chart. Bryant 915S = 59SC5 chart. Payne/ICP siblings exist. A rooftop 48FC IGC 2-flash is not this IFC.
5 Pick the plate — 32 and 41 lie across sisters
Count pressure switches. One = Comfort 96 (59SC5/SC6) — do not hunt high-fire. Two = Performance 59TP6 or Infinity two-stage 59TN6. No discrete PS + ABCD wall control = 59MN7 modulating. 41 is blower RPM on VS / 18-speed (59TP6, 59SC6), not a PSC Comfort heat tap. 21 = valve relay or the wrong model plug left in the cabinet.
Expect: 59TP6 vs 59SC5 vs 59MN7 vs 58STA named from the rating plate.
If it fails: Load that model in Diagnose and type the live two-digit (59TP6 32, 59SC5 31, 59MN7 31).
Field notes
- 11 = no stored history (power was pulled). 12 = blower after power-up on a W call. 22 = flame with valve off. 24 = 24 V fuse. 45 = control lockout — find the root digit first.
- Rheem 33 is rollout. Carrier 33 is limit/rollout as a circuit. Do not mix brand tables.
- Type the live pair with the model. 3-flash language belongs on Goodman / Lennox Merit / rooftop IGC, not here.
Related
Sources
Practice distilled from public HVACR School and AC Service Tech material. OEM I/O and EPA 608 still win.