STEADY ON
Fraser-Johnston
Control Board Powered, No Call for Heat or Internal Board Fault
LED on control board is solid on with no flashing; furnace does not respond to thermostat.
Advertisements
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Advertisements
Possible Causes
No 24 VAC signal from thermostat, Open transformer secondary, Blown low‑voltage fuse on IFC board, Failed integrated furnace control (IFC) board
How to Fix / Troubleshooting
Safety first: Turn off power before checking wiring. Low‑voltage circuits can still be damaged by shorts.
- Check thermostat settings: Ensure thermostat is set to HEAT and the setpoint is above room temperature. Replace thermostat batteries if applicable.
- Inspect low‑voltage fuse: Locate the 3–5 amp automotive‑style fuse on the IFC board. If blown, replace with the same rating. If it blows again immediately, there is a short in the thermostat wiring or accessory circuits.
- Check R and W terminals: With power on and a call for heat, measure 24 VAC between R and C, and then between W and C. If there is 24 VAC at R but not at W, the thermostat or wiring is open.
- Inspect transformer: If there is no 24 VAC at R and C, the low‑voltage transformer may be open or not receiving 120 VAC. This should be tested and replaced by a technician.
Advertisements
Repair Difficulty
Medium
3/5
Required Part
Integrated Furnace Control Board
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements