Lennox ML193UHE furnace slow red flashing: Normal Idle Status
Info — not a fault
What does a slow red LED blink mean on a Lennox ML193UHE with ignition control 103217-03? This is a normal status. The control is idle with no heat demand, running the fan continuously, or operating in cooling mode.
Safe checks before calling
If you expected heat, confirm the thermostat is set to HEAT, the setpoint is above room temperature and the fan is on AUTO. A fan set to ON can circulate unheated air.
Questions about this code
What does a slow red LED blink mean on a Lennox ML193UHE with ignition control 103217-03?
This is a normal status. The control is idle with no heat demand, running the fan continuously, or operating in cooling mode.
Does Lennox ML193UHE furnace slow red flashing mean I need a repair?
No repair is indicated by this state. If the thermostat shows a heat call but the LED keeps this slow blink, the control is not registering that demand; a technician should check the thermostat connection.
How much does it cost to fix Lennox ML193UHE furnace slow red flashing?
This normal state by itself implies no repair bill. Cost only comes into question if a heat call is not reaching the control and a technician has to trace why.
Applies to
ML193UHE
Different Lennox generations use different code maps. If your series isn't listed, don't assume this meaning — check your blower-door label.
Verified against Lennox ML193UHE Installation Instructions, p.39
Verified against Lennox ML193UHE Unit Information / Service Literature, p.9
Last verified 2026-10-07 · page updated 2026-10-07 · how we verify
Related Lennox furnace codes
These codes use the same lennox ml193uhe with ignition control 103217-03 system.