Error Code Continuous ON
Info

Bryant 355MAV Error Code Continuous ON: Normal Operation

TL;DR
Your Bryant 355MAV is in normal standby mode. The continuously lit LED means the control has power and is ready to respond to a thermostat call for heat.
Disclaimer
This article is for informational purposes only and does not guarantee the accuracy or completeness of the information provided. Always turn off power and gas supply before attempting any repairs. If you smell gas, leave immediately and call your gas company. Consult a licensed HVAC technician for diagnosis and repair. Any actions taken based on this information are at your own risk.

What Does Code Continuous ON Mean?

A continuously lit (solid on) LED on the Bryant 355MAV's control board means the furnace has 24 VAC power and is operating normally in standby mode. This is the expected status when the furnace is powered on and waiting for a call for heat from the thermostat. No error condition is present.

The Bryant 355MAV uses a variable speed furnace control with a two-digit diagnostic code system. The continuous on status is distinct from the numbered fault codes, which use combinations of short and long flashes. A solid LED confirms that both the 115 VAC line voltage and the 24 VAC control voltage are present and the control board is functioning correctly.

If the furnace is not heating despite the LED being on, the issue is likely with the thermostat connection or settings rather than the furnace itself. Verify that the thermostat is set to heat mode, the target temperature is above room temperature, and the R and W thermostat wires are securely connected at both the thermostat and the furnace control board.

Contact a licensed HVAC technician if any of these apply:

Sources

  1. Bryant 355MAV Series I Installation, Start-up, and Operating Instructions

✓ Verified against manufacturer service manual — March 2026