Carrier · Status code
Carrier 59TN7A status code 34: ignition fault or flame lost after ignition
Major code 34 covers ignition and flame-loss events on the Infinity 97. Minor 34.1 means ignition failed during four consecutive trials. Sub-codes 34.5 through 34.8 record flame lost after successful ignition, by stage (low or high heat) and by timing (before or after the blower on-delay finished).
On the control
- Code
- 34
- Minor
- 34.1 · 34.5 · 34.6 · 34.7 · 34.8
- Door LED
- 3 short flashes then 4 long
- Controller
- 59TN7A integrated furnace control with 3-digit LCD display and door LED
- Applies to
- Carrier Infinity 97 (59TN7A)
- Manual
- 59TN7A-01SI
What each minor code says, verbatim
| Display | Manufacturer wording |
|---|---|
| 34.1 | Ignition fault - four consecutive ignition trials. |
| 34.5 | Low heat flame lost before blower on-delay |
| 34.6 | Low heat flame lost after blower on-delay |
| 34.7 | High heat flame lost before blower on-delay |
| 34.8 | High heat flame lost after 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. Testing includes flame-signal measurement through the stage transitions.
Which furnaces this applies to
Documented for Carrier 59TN7A Infinity 97 furnaces in installation instructions 59TN7A-01SI, Fig. 61 service label.
Scope: Carrier 59TN7A Infinity 97 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 how long the furnace runs before the code appears and whether the fault is on low or high fire. Check for water around the furnace and blockage at the vent terminations.
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 in the cycle.
Related components and symptoms
Questions people ask
Why does this label skip sub-codes 34.2 through 34.4?
Sub-code numbering follows Carrier's shared label template: the Infinity 97 prints 34.1 (ignition) and the two-stage rows 34.5 to 34.8, with the intermediate numbers reserved for other platform variants. Read the label on your own furnace.
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.