Bryant 355MAV Error Code Continuous ON: Normal Operation
What Does Code Continuous ON Mean?
On the Bryant 355MAV, a steady (continuous-ON) status LED is the control board telling you it is healthy and powered. It confirms the Variable Speed Furnace Control has its 24 VAC supply and is sitting in normal standby, waiting for a call for heat.
This is the state the board should rest in whenever the furnace is idle. It sits opposite the continuous-OFF indication (no power) and the rapid-flashing indication (reversed line voltage polarity). Seeing a solid light means neither of those power problems is present.
A steady LED does not by itself prove the furnace will heat — it only confirms board power. If the thermostat calls and the burners still do not light, the board will typically flash a two-digit status code describing the specific fault. In normal standby, though, a solid light is exactly what you want to see.
What You'll Notice
- The status LED shines steadily with no flashing while the furnace is idle
- When the thermostat calls for heat, the furnace begins its normal inducer, ignition, and blower sequence
How This Is Diagnosed
Confirming normal standby is simple: with the furnace idle and the blower door seated, the LED should be a single steady light rather than off or flashing. That directly indicates the board is seeing 24 VAC at its secondary terminals. If you then raise the thermostat setpoint, the light should give way to a normal heating sequence, confirming the board is not only powered but responsive. If it stays solid and nothing happens, the issue lies with the thermostat, its wiring, or a downstream component rather than board power.
- The LED is steady on but the furnace never ignites when the thermostat calls for heat after you confirm thermostat settings and wiring
- The light is solid yet the home is not reaching temperature, pointing to an airflow or heating issue rather than board power
Frequently Asked Questions
My Bryant 355MAV light is solid — is something wrong?
No. A continuous-ON LED is the normal standby indication and means the board has power and is ready to run. It is the flashing two-digit codes, not the steady light, that report faults.
The light is on but the furnace won't heat. What now?
A steady light only confirms board power, not a successful heating cycle. Verify the thermostat is set to heat above room temperature, then watch the LED during an actual call for heat — if a fault exists, the board will flash a two-digit code you can look up.
Sources
✓ Verified against manufacturer service manual — March 2026