Lennox Furnace Error Code LED#1 Slow Flash / LED#2 Slow Flash (simultaneous)

This LED pattern means the furnace is powered on and operating normally. It is not a fault or error code. The same pattern also appears during cooling mode and when the thermostat is set for continuous fan operation. No corrective action is required when you see this display.

Yes, this condition is completely safe. The simultaneous slow flash of both LEDs is the control board's way of signaling that no faults have been detected and the system is in a normal operating state. The furnace is safe to continue running under this indication.

There is no repair cost associated with this LED pattern because it indicates normal operation rather than a fault. If you called a technician to diagnose this condition alone, you would typically pay only a standard diagnostic or service call fee, which generally ranges from $75 to $150 depending on your area. Any additional costs would only apply if the technician identifies a separate, unrelated issue during the visit.

No repair is needed for this LED pattern because it indicates normal operation. If the furnace is not heating or cooling as expected despite this status display, the issue is likely unrelated to the control board itself. In that case, check the thermostat settings, gas supply, and air filter as a starting point.

A reset is not necessary and will not change this pattern, because it is not a fault code to begin with. Power-cycling the unit will simply cause the board to reinitialize and return to this same normal-operation display once startup is complete. Resets are only useful for clearing actual fault codes stored on the board.