York / Coleman / Luxaire · Furnace error code

Rapid amber flashLow flame signal

Single source High-voltage / caution

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OnCall Tech is a reference tool for trained technicians and can make mistakes. Always disconnect power and confirm with the manufacturer's documentation before you work.

Related diagnostic guides

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Furnace short cycling (starts and stops quickly)

Short cycling is usually a safety opening mid-cycle (limit from low airflow, flame sensor dropping out, pressure switch opening) or a thermostat issue. Read the code and time the cycle.

4 steps ~45 minmoderate

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Furnace runs no heat (blower only or nothing)

Start with the board LED code, then work the call path: thermostat, 24 V, safeties, inducer, ignition, flame proving. Most no-heat calls end at a filter, a flame sensor, a pressure switch issue or gas being off.

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Igniter glows but burners never light

If the igniter glows and no flame appears, the problem is on the gas side (supply off, valve not opening, valve not receiving 24 V). You can confirm the gas shutoff is open and whether the board sends the valve signal; the valve and gas pressure are licensed-technician work.

3 steps ~30 minadvanced