LED flashes code 44; furnace may lock out or show erratic ignition behavior.

Safety: Line voltage work should be done with power off and ideally by a qualified person. Incorrect polarity and grounding can be hazardous.

Steps:

• Check power polarity: At the furnace disconnect or junction box, verify that hot (black) and neutral (white) are correctly connected. The furnace should not be wired with reversed polarity.
• Verify ground: Ensure the green or bare ground wire is securely attached to the furnace chassis and to the electrical panel ground.
• Inspect neutral connections: Look for loose neutrals in the furnace junction box and on the control board neutral terminal strip.
• Eliminate shared circuits: If the furnace shares a circuit with other large loads, consider having an electrician place it on a dedicated circuit.

When to call a technician: If code 44 persists after correcting wiring and grounding, the control board ignition circuit may be defective and should be replaced by a professional.