York furnace Solid LED: Control fault detected

A steadily lit LED of any colour means the control has detected a fault in itself. York notes that solid LED error codes are not included in the stored fault code replay.

Applies to: York, Luxaire and Coleman gas furnaces using the UTEC integrated furnace control boards documented in technical service letter ST-045-09. York specifies a solid LED of any colour indicates this condition.

What it means

York's table specifies that a solid LED of any colour indicates a control fault detected — the colour does not narrow it further, which is unusual and worth knowing. The board has found a problem within its own operation rather than in the furnace's mechanical parts. There is also a documented limitation that matters practically: solid LED error codes are not displayed during fault code retrieval. So a control fault that has since cleared leaves no trace in the history, unlike the flash codes marked as stored in the error array.

Most common causes

• An internal control board fault.
• A microprocessor or internal check failure.
• Electrical damage to the control from a surge.
• Water damage to the control board.
• A control approaching the end of its service life.
• A supply problem the board's internal checks have flagged.

How to diagnose it

1. Confirm the LED is genuinely steady rather than flashing, since heartbeat patterns on these boards are normal operation.
2. Note that the colour does not matter — York specifies a solid LED of any colour indicates this condition.
3. Note whether there was a recent power surge, storm, or electrical event.
4. Check whether the furnace or its surroundings have been wet.
5. Do not expect this to appear in the stored fault replay, since York documents that solid LED codes are not displayed.

How to fix it

1. Try one power reset — off at the service switch for about thirty seconds, then on. A transient condition may clear.
2. If the indication returns, the control board needs a technician.
3. If the furnace has been wet, do not power it up. Have it inspected first.
4. If a surge is suspected, consider whether surge protection is worth fitting, since replacing a board without addressing a recurring cause invites a repeat.

Notes

The exclusion of solid LED codes from the stored history is a real gap. An intermittent control fault leaves no record, which means noting the date and time when you see one is the only way it gets captured.

Related

• Fault code retrieval — How to read and clear stored fault codes
• Rapid red flashing — Twinning error or incorrect 24 volt phasing

All codes for this manufacturer

York, Luxaire and Coleman furnace flash codes — every code, with what differs between models.

Sources

• Johnson Controls Unitary Products technical service letter ST-045-09 — York UTEC furnace boards, fault code tables and retrieval procedure