Carrier Error Code 24: Secondary (24 V) fuse open (Furnace)
Carrier error code 24 on a furnace means: Secondary (24 V) fuse open. It is also called Carrier diagnostic code 24.
Homeowner? What Carrier code 24 means for you
Check, then call Your furnace is reporting: Secondary (24 V) fuse open. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Safe things you can check yourself
- Check the thermostat: right mode (Heat or Cool), set a few degrees past room temperature, and fresh batteries if it uses them.
- Make sure the unit has power: its on/off switch (often looks like a light switch near the unit) is ON and the breaker in the electrical panel is not tripped.
- Make sure the furnace front door or panel is closed properly; many furnaces will not run with the door switch open.
- Look at the air filter. If it is grey and clogged, replace it; a blocked filter causes many shutdowns.
- Outside, make sure the intake and exhaust pipes or vent cap are not blocked by snow, ice, leaves or a nest.
- Check that the gas valve next to the furnace is open (handle in line with the pipe). Do not force it.
- Try one reset: turn the power off for 30 seconds, then back on. If the code comes back, stop resetting and call a technician.
Call (647) 657-2977Book a service call
Licensed technicians serving Vaughan, Toronto and the GTA.
What does Carrier error code 24 mean?
The 3-amp automotive-type fuse in the 24-V circuit on the control has blown.
Applies to: 59TP6A two-stage variable-speed ECM multipoise condensing gas furnace, all sizes (040-10 to 120-22)
Common causes of Carrier code 24
- Short in 24-V wiring including thermostat leads
- Short in outdoor unit low-voltage wiring
Carrier models that use code 24
Show all 22 models
58SB0A045E14--1258SB0A045E17--1258SB0A070E14--1258SB0A070E17--1258SB0A070E17--1658SB0A070E21--1658SB0A090E17--1458SB0A090E21--1658SB0A090E21--2058SB0A090E24--2058SB0A110E21--2058SB0A110E24--2058SB0A135E24--2058SB0A155E24--2059TP6A040-1059TP6A040-1259TP6A060-1259TP6A060-1459TP6A080-1659TP6A080-2059TP6A100-2059TP6A120-22
Other Carrier Furnace codes
All Carrier Furnace error codes →
Carrier code 24: homeowner questions
What does Carrier code 24 mean?
Secondary (24 V) fuse open. The 3-amp automotive-type fuse in the 24-V circuit on the control has blown.
Is it safe to keep using my furnace with code 24?
It depends on the cause. This is often caused by something simple. Try the safe checks below; if the code returns, book a service call before it turns into a no-heat or no-hot-water emergency.
Can I reset Carrier code 24 myself?
You can try one reset (power off for 30 seconds, then on). If Carrier code 24 comes back, the cause is still there and a licensed technician should check it.
Who can fix Carrier code 24 near me?
Aurora Star Tech Inc. repairs Carrier furnaces in Vaughan, Toronto and across the GTA. Call (647) 657-2977 or book a service call online.
Homeowner help: Furnace Not Turning On: What to Check · Furnace Blinking Light: What the Flash Codes Mean
Troubleshooting guides
- Blowing cold air All brands · Furnace
- No heat All brands · Furnace
- Short cycling All brands · Furnace
- Burners will not light or stay lit - Carrier 58SB0A/58SB1A Carrier · Furnace
- Furnace not responding to thermostat - Carrier 58SB0A/58SB1A Carrier · Furnace
Source: Carrier 59TP6A Installation, Start-up, Operating and Service Instructions, Fig. 66 Troubleshooting Guide (cont.), p.89; p.76. Written in our own words as a summary; always check the original manual.
General guidance for qualified technicians. The manufacturer's installation and service manual and local codes always take priority. Aurora Star Tech is not affiliated with, endorsed by or sponsored by any equipment manufacturer; brand and model names are used only to identify equipment and belong to their owners.