York Steady Off Error Code
LED is steady off — no power to the control, or the control has suffered catastrophic damage.
Source: York 3/York_INSTALLATION-MANUAL-ZX-A7-08-TO-14-SER_InstallationGuide_HVAC_EN-5513316-uim-c-0819.pdf
What does York Steady Off mean?
A completely dark ignition control LED means the board is not displaying any status. Per York's flash-code table this signals one of two conditions: less than 18 VAC is present at the control's R and C connections, so the board has no power; or the control has suffered catastrophic damage that prevents the LED from working. In both cases the output relay contacts stay open, so inducer and gas valve operation are not permitted.
Symptoms
- Ignition control LED shows no light at all
- No heat; inducer and gas valve never energize
- Possible visible physical damage on the control board
- Burners do not fire on a call for heat
Common causes
- Less than 18 VAC reaching the control's R (P2-2) and C (P2-1) pins
- Tripped 3.2A control circuit breaker or open phase-monitor contacts
- Failed or open 75VA transformer secondary
- Catastrophic control board failure
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Diagnostic steps
Verify primary transformer voltage
Check that line voltage is present at the primary of the 75VA transformer and that 24 VAC is present at its secondary.
Check the control circuit path
Verify 24 VAC from the UCB's C to SD terminals, confirming the 3.2A control circuit breaker and phase-monitor contacts are closed.
Measure voltage at the control
Confirm 24 VAC is present at the ignition control's R (P2-2) and C (P2-1) connections and that the unit-to-control wiring is intact.
Inspect for board damage
Look for visible physical evidence of damage on the board; if found, the control must be replaced.
When to call a professional
Diagnosing a steady-off control means working inside the electrical box with live line voltage, which is hazardous. If you confirm 24 VAC is present at the R and C pins but the LED stays dark, the board has failed and must be replaced — call a licensed HVAC technician. Any sign of a tripped breaker, blown transformer, or phase-monitor fault also warrants professional diagnosis to find why the protective device opened.
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Other York Error Codes
Normal operation — the ignition control board is powered and ready to respond to a heating demand.
LED is steady on — the control's microprocessor has not passed its self-check.
Induced draft pressure switch did not close — the switch failed to prove airflow within 10 seconds of the inducer starting.
Induced draft pressure switch stuck closed — the switch reads closed at the same moment a call for heat begins.
Flame could not be established — no flame was sensed in three consecutive ignition attempts (lockout).
Flame loss — an established flame dropped out five times during one heating cycle (lockout).
Open limit — 24 VAC was lost at the limit-switch input for six minutes or less during a call for heat.
Open rollout — 24 VAC was lost at the control's flame rollout switch input.
Gas valve failed to shut off — flame was sensed for more than 2 seconds after the gas valve output was turned off.
Indoor airflow failure / open limit — limit input lost 24 VAC for more than six minutes during a call for heat (hard lockout).
Gas valve miswire or gas valve relay fault — unexpected or missing 24 VAC at the gas valve outputs.