Carrier fault codes

Drive is enabled but stays at min Hz or 0 because analog / serial speed is missing.

3 plates

Example on most Carrier/Bryant packaged CES IGC stickers: pressure switch / draft did not make. Confirm the sticker in THIS heat section — revisions differ.

2 plates

Example on many CES rooftop IGC stickers: limit open. Confirm THIS sticker.

2 plates

Example: rollout / aux limit on many CES stickers; consecutive limit on others. Read THIS IGC.

2 plates

Example on many CES rooftop IGCs: ignition lockout after retries. Confirm THIS sticker.

2 plates

Example: internal control / valve circuit on current CES rooftop stickers. Power-cycle once; if 8-flash returns, valve ohms then IGC.

2 plates

Memory empty or power was cycled.

7 plates

Powered up on a W call.

7 plates

Hardened 33. Limit/rollout stayed open.

7 plates

Airflow or rollout. 13 is the hardened 33.

1 plate

Hardened 34. Auto-reset ~3 h.

7 plates

No flame prove. 14 is the hardened 34.

1 plate

Valve relay fault, or missing/wrong model plug on boards that use one.

7 plates

Flame sense while GV de-energized.

7 plates

Draft switch still made when it should be open.

7 plates

24 V fuse on the IFC.

13 plates

Category I draft will not prove. NEVER a PVC condensate trap.

10 plates

Two-stage draft path. 31 is the active-stage / draft prove; 32 is low-fire PS. Unlike 59MN7, these are discrete switches.

2 plates

Modulating inducer did not hit the pressure band for the commanded firing rate. Not a discrete two-stage PS.

1 plate

If this door card lists 32, it is the same single draft switch as 31 — not 59TP6 low-fire and not a missing high-fire hose. One switch, one hose.

5 plates

Airflow or flame-containment. Dirty A-coil on an 80% is the winter/summer crossover call.

7 plates

Airflow or flame-containment. 13 is the hardened 33.

5 plates

Trial without flame sense. Repeats → 14.

7 plates

HSI / gas / rod. 14 is the hardened 34.

5 plates

Infinity VS motor not at commanded CFM.

7 plates

VS motor vs setup.

1 plate

Inducer not at commanded speed.

2 plates

Blockage or disconnected hose.

2 plates

CFM learn failed.

2 plates

IFC parked itself.

5 plates

Leak sensor or mitigation input on an R-454B cabinet.

1 plate

Wall control or outdoor dropped off the bus.

5 plates

JADE LCD: ACT ERROR / ACT RANGE. Actuator did not follow command. Feedback pot off the shaft is the weekly.

3 plates

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

6 plates

Wrong charge method is as common as wrong charge.

6 plates

JADE LCD: CO2 / SENS ERR. DCV sensor failed or the 0–10 V input is floating. Damper holds open; compressor never runs.

3 plates

Drive or bus. Wall control loses the outdoor.

6 plates

Outdoor dropped off ABCD.

3 plates

Will not pull, chatters, or is welded.

9 plates

Stuck in defrost or never defrosts.

1 plate

On this family that is often a restricted secondary, not a 59TP6 trap lecture alone.

1 plate

Float switch or tripped condensate opened 24V.

3 plates

Start here when the hood is the complaint. Title 24 FDD classes: sensor, not-economizing, false-economizing, damper not modulating, excess OA.

3 plates

Strips not coming on, or on when they should not.

1 plate

Drive has line voltage but will not run — the unit board never enabled it.

3 plates

Damper open past the commanded minimum with no economizer or DCV request.

3 plates

Damper open with OA above changeover. Space hot, high OA bills, or wet coil.

3 plates

Controller did not see blower current / pressure.

3 plates

Flame present then dropped, or µA too low to prove.

2 plates

JADE LCD: FREEZING. Mixed air below the low-limit. Damper drives shut; mechanical cool may lock.

3 plates

Keypad example: GF. Drive sees current to ground on the motor leads.

3 plates

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

9 plates

Still real on an inverter.

3 plates

Trial for ignition failed after the IGC retries.

2 plates

L5/L4-class faults on the drive.

3 plates

No 24V at the ignition control, or the module is dead.

2 plates

Heat-exchanger or supply limit opened.

2 plates

Restricted secondary raises head and can open rollout / limit.

1 plate

Drive is running too slow to close the prove switch, so the unit board reports fan fail. Reliatel example: Fan Fail with the drive still at min Hz.

3 plates

Suction dropped out the low-pressure switch.

3 plates

JADE two-line LCD: MA / SENS ERR. Mixed-air sensor failed. This one alarms immediately on power-up — others wait the 60-minute setup window.

3 plates

Wall-control setup indoor/outdoor size does not match the device on the bus. A setup, not a pressure switch.

1 plate

Damper is two-position (0 or 100) instead of tracking 2–10 V. Title 24 FDD class.

3 plates

OA is in the free-cooling window and the damper stayed shut. Title 24 FDD class.

3 plates

JADE LCD: OA / SENS ERR (or OA SYLK ERR). Outside-air thermistor failed or lost SYLK. Board thinks the roof is 20 °F or 120 °F.

3 plates

Keypad example: oC (Yaskawa) or OC. Output current trip. Locked rotor, dirty filters, or FLA set too low.

3 plates

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

6 plates

Keypad example: oH. Drive thermal trip.

3 plates

Keypad example: ov (Yaskawa) or OU. DC bus high. Usually regen on decel, not a new drive.

3 plates

Keypad example: PF. Missing or imbalanced incoming phase.

3 plates

Three-phase monitor opened.

3 plates

Inducer ran (or should have) and the draft switch did not make.

2 plates

JADE LCD: RA / SENS ERR. Return-air thermistor failed. Differential / enthalpy changeover compares OA to RA.

3 plates

Flame left the burner box.

2 plates

Reversing valve did not stroke.

1 plate

Supply or return smoke detector, or a firestat, has the unit locked out.

3 plates

Flame with no trial.

2 plates

Keypad example: Uv (Yaskawa) or LU. DC bus dropped. Incoming power or a missing phase.

3 plates

The indoor fan is a drive, not a contactor + cap. Type the keypad string: oC, Uv, ov, GF, oH, PF.

3 plates