Error Code Continuous ON
Info

Bryant 340MAV Error Code Continuous ON: Normal Operation

TL;DR
A continuously illuminated LED means the furnace has 24VAC power and is in normal standby — no heating call is active. No action is needed.
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?

When the diagnostic LED on the Bryant 340MAV control board glows continuously without flashing, the furnace is in normal standby mode. The integrated furnace control has 24VAC power and is operating correctly, but no call for heat is active from the thermostat — the R-W contacts are open.

This status appears between heating cycles after a call for heat ends and the circulating blower shuts down, or any time the thermostat is satisfied. If the furnace is part of a system with central air conditioning, the continuous LED may also appear during cooling or fan-only operation since those modes operate independently of the gas heating circuit.

The 340MAV uses a 2-digit LED blink code system where the first digit is the number of short flashes and the second is the number of long flashes. A continuously illuminated LED is distinct from all blink codes and simply indicates a powered, idle state.

Contact a licensed HVAC technician if any of these apply:

Sources

  1. Bryant 340MAV J-Series Installation and Service Instructions

✓ Verified against manufacturer service manual — March 2026