Unfortunately, the user manual of the Trane XR90 furnace offers no explanation of what the blinking light means that can be seen behind a small hole in the bottom front panel of this high-efficiency gas furnace.
The codes are explained on a wiring diagram that is glued to the back of the panel.
Trane XR90 Diagnostic Codes
A continuously blinking light indicates normal operation and is no reason for concern. Here is the complete list:
- Flashing slow: Normal – no call for heat
- Flashing fast: Normal – call for heat
- Continuous on: Replace IFC (circuit board)
- Continuous off: Check power
- 2 Flashes: External lockout (retries or recycles exceeded)
- 3 Flashes: Pressure switch error
- 4 Flashes: Open limit device
- 5 Flashes: Flame sensed when no flame should be present
- 6 Flashes: 115 VAC power reversed polarity or poor grounding
- 7 Flashes: Gas valve circuit error
- 8 Flashes: Low flame sense signal
- 9 Flashes: Check igniter
Dr. Heet does not provide support or repair advice for this type of furnace. Please contact a licensed HVAC professional if your furnace does not function properly.