HVACopedia

Carrier · Furnace

24.1 Fuse fault (24 V)

High severity 59SC6A

What the control is telling you

The 3-amp automotive blade fuse on the control's 24 V circuit is open.

Applies to: Carrier 59SC6A

Likely causes

  • Short in thermostat wiring
  • Short in accessory wiring (humidifier, outdoor unit control)
  • Shorted 24 V component

Test and repair steps

  1. Warning: Turn off power before touching the fuse.
  2. Confirm the 3-amp automotive blade fuse on the control is open.
  3. Find the short first disconnect thermostat wires and check R and each terminal to C for a short.
  4. Check humidifier (24 VAC HUM, 0.5 A max) and outdoor unit/accessory wiring for shorts or chafing.
  5. Replace with a 3-amp fuse ONLY.
  6. Restore power and run heat, cool and fan to confirm the fuse holds.

Settings for these units

Save it for the next call

Star this code in the HVACopedia app and keep the whole library on your phone for jobs with no signal.

Open the app

Source: Carrier 59SC6A Installation, Start-up, Operating and Service Instructions, Fig. 60 Service Label p.54; Fig. 61 p.56; Electrical Controls and Wiring p.62. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.