Status LED on Lennox furnace control board flashes 6 times; furnace may not respond to thermostat.

Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Reversed hot and neutral at furnace, Open equipment ground, Shared neutral with other loads causing noise, Faulty power supply wiring to Lennox furnace

How to Fix / Troubleshooting

Danger: This involves 120/240V. Turn off power at breaker. If you are not qualified, call an electrician.

1. Inspect junction box: Verify hot, neutral, and ground are correctly connected per code.
2. Confirm ground: Ensure the ground wire is securely attached to the furnace chassis.
3. Correct polarity: If reversed, correct wiring at the nearest junction or panel.

Repair Difficulty

Professional Required 5/5