Carrier · Status code
Carrier 59SC6A status code 34: ignition fault or flame loss
Major code 34 covers the ignition sequence on the Comfort 96. Minor 34.1 means ignition failed during four consecutive trials; minors 34.2 and 34.3 mean flame was proven and then lost, either before or after the heating blower on-delay finished.
On the control
- Code
- 34
- Minor
- 34.1 · 34.2 · 34.3
- Door LED
- 3 short flashes then 4 long
- Controller
- 59SC6A integrated furnace control with 3-digit LCD display and door LED
- Applies to
- Carrier Comfort 96 (59SC6A)
- Manual
- 59SC6A-01SI REV D
What each minor code says, verbatim
| Display | Manufacturer wording |
|---|---|
| 34.1 | Ignition fault - during four consecutive ignition trials. |
| 34.2 | After successful ignition (flame proven) flame loss before heating blower on delay. |
| 34.3 | After successful ignition (flame proven) flame loss after heating blower on delay. |
A code is a condition, not a diagnosis
An ignition fault points at gas supply, the ignitor, flame sensing or combustion air. Flame proven and then lost points at the flame-sensing path or at conditions that snuff the flame: a fouled sensor, condensate dripping onto the burner area, venting disturbance or a gas supply that drops after light-off. Testing includes flame-signal measurement during the transition.
Which furnaces this applies to
Documented for Carrier 59SC6A Comfort 96 furnaces in installation instructions 59SC6A-01SI REV D. Only sub-codes 1 through 3 are printed on the single-stage Comfort label; the two-stage labels carry their own 34.x set.
Scope: Carrier 59SC6A Comfort 96 furnaces with the on-board 3-digit display control. Not sure which control you have? Send us the full model number from the rating plate.
Safe things to look at first
- Read the full code on the control display through the door, including any minor digit (for example 33.2), and write it down.
- Look, without touching, for obvious conditions you can report: snow or ice at the vent terminations, water on the floor, a loaded filter, a condensate pump that is full or off.
- Note whether the furnace still heats at all, and how long it runs before the code returns.
- Note whether the furnace lights at all and how long it runs before the code appears.
- Check the floor around the furnace for water and the vent terminations for blockage.
Do not
- Do not bypass or jumper the door switch, limit switches, rollout switches or pressure switches.
- Do not open the burner compartment, disconnect tubing, or adjust the gas valve or gas pressure.
- Do not keep cycling power to force the furnace to relight; repeated resets hide the fault and can allow unburned gas to build up after ignition failures. If the code returns, stop and call.
What a technician does
- A technician measures the flame signal through a full cycle, inspects the flame sensor, its wiring and the burner area, and checks gas supply pressure and venting when the fault repeats at the same point every time.
Related components and symptoms
Questions people ask
What is the difference between 34.1 and codes 13.x?
On this label 13.2 also covers an ignition lockout after four tries. Codes can overlap across majors by design; the stored fault history and the exact minor digits tell the technician which event the control recorded most recently.
Why does 34.3 appear only on cold days?
Flame loss after the blower starts in cold weather often traces to venting or condensate: ice at the termination, a sagging vent holding water, or a drain that freezes mid-cycle.
Seeing code 34 on your Carrier?
Tell us the full code, the model number and whether the furnace still heats on low. BC Wide prioritizes no-heat calls across Greater Vancouver.