Carrier · Status code
Carrier 59SC6A status code 33.1: a switch has opened in the main limit circuit
Status code 33.1 means a switch in the main limit circuit has opened. The main limit circuit includes the manual-reset switch in the burner area that opens on flame rollout; Carrier states it must never be jumpered and must be reset only after the cause is corrected.
Smell gas?
- Do not operate light switches, appliances or phones inside.
- Leave the building and leave the door open behind you.
- From outside, call the FortisBC emergency line at 1-800-663-9911 or 911.
- Only after that, call BC Wide about the furnace.
A furnace that will not run is a breakdown, not a gas emergency. Gas smell, a CO alarm, soot or scorching are.
On the control
- Code
- 33
- Minor
- 33.1
- Door LED
- 3 short flashes then 3 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 |
|---|---|
| 33.1 | A switch has opened in the Main Limit circuit |
A code is a condition, not a diagnosis
A switch in the main limit circuit opens from overheating in the airflow path (a loaded filter, closed registers, a blower fault, undersized ducts) or from the rollout side of the circuit responding to a combustion problem. Airflow measurement and a combustion check distinguish these; the code is a condition, not a part.
Which furnaces this applies to
Documented for Carrier 59SC6A Comfort 96 furnaces in installation instructions 59SC6A-01SI REV D. On the single-stage Comfort label, 33.1 is the only sub-code printed under major 33.
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.
- Report any warm smell, whether the blower runs, and the filter condition.
- If you smell gas, leave the building and call FortisBC at 1-800-663-9911 or 911 first.
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 checks every switch in the main limit circuit, measures temperature rise and static pressure, and confirms the cause of any rollout before resetting a manual-reset switch.
Related components and symptoms
Questions people ask
What is the main limit circuit on my furnace?
It is the series of safety switches that stop the burner if the furnace overheats, including the limit switch near the heat exchanger and the manual-reset switch in the burner area that responds to flame rollout.
Seeing code 33 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.