Carrier and Bryant 24 Error Code: Secondary voltage fuse is open
Updated October 2026 · Sourced from Carrier and Bryant documentation
Carrier and Bryant 24 means different things on different series:
- Carrier 59SC5A single-stage 4-way multipoise condensing gas furnace (Series 1 and 2): The 24VAC fuse is open. The label says to check for a short circuit in the secondary voltage (24VAC) wiring.
- Bryant 926TC two-stage variable-speed ECM multipoise condensing gas furnace: The control reports a fuse fault. The 926TC manual elsewhere says status code 24.1 is displayed when the fuse needs to be replaced.
Is it safe to keep running? No. Turn it off and get it checked. Call a licensed technician to find the short in the low voltage wiring before the fuse is replaced.
24 at a glance
| Code / how it shows | Meaning | Applies to |
|---|---|---|
| 24 Status LED flashes: first digit is short flashes, second digit is long flashes | Secondary voltage fuse is open | Carrier 59SC5A single-stage 4-way multipoise condensing gas furnace (Series 1 and 2) |
| 24 Also: 24.1 Status LED flashes: first digit is short flashes, second digit is long flashes; display shows 24.1 | Fuse fault | Bryant 926TC two-stage variable-speed ECM multipoise condensing gas furnace |
Check this first
Only steps a homeowner can do safely. Do not open electrical panels or the burner area.
- Turn the furnace power off at the switch or breaker, wait one minute, then turn it back on to see whether the code returns.
🛑 Stop and call a licensed pro if
- Call a licensed technician to find the short in the low voltage wiring before the fuse is replaced.
- Call a licensed technician to find the cause of the blown fuse in the low voltage wiring.
- You smell gas. Leave the house, do not touch switches, and call your gas utility from outside.
- Flame rollout, limit or pressure switch codes that come back after one reset.
- Anything involving the control board, gas valve, flame sensor, igniter or venting.
- A carbon monoxide alarm sounds. Get everyone outside and call 911 or the fire department.
Safe first steps for any Carrier and Bryant code
- Count the LED flashes through the blower door window before you switch anything off. Cutting power can clear the code.
- Replace or clean the furnace air filter.
- Check the thermostat: correct mode, set above room temperature, and fresh batteries.
- Make sure the furnace power switch and breaker are on. If the furnace has locked out, turning the power off and back on once restarts it.
- Make sure the gas valve is in the ON position, following the lighting instructions on the furnace label only.
- On high-efficiency furnaces, look at the outside vent and intake pipes for snow, ice, leaves or nests (look only, do not take pipes apart).
Sources: Carrier 59SC5A Installation, Start-up, Operating and Service and Maintenance Instructions, Fig. 62 Service Label, p.67; Bryant 926TC Installation, Start-up, Operating and Service and Maintenance Instructions, Service Label (Status Code Table), p.56. Codes are series-specific, so your unit's own manual is the final word. Reviewed October 2026.
Shaun Cain · Certified HVAC & Refrigeration Technician · Ask an HVAC technician